cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

User: Rachel Wofford

Rachel Wofford's wiki page.

Rachel Wofford has authored 10 sequences.

A343800 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(6,n) (with n at least 4) missing three edges, where exactly two removed edges are incident to the same vertex in the 6-point set and exactly two removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

978064, 86336272, 6348047008, 430432446400, 28099268578864, 1801251897183472, 114448204851788608, 7240412761411376800, 457083355837815526864, 28825337854868779198672, 1816898392511988031818208, 114492570488330137017059200, 7213899161676798784740778864
Offset: 4

Author

Rachel Wofford, Apr 29 2021

Keywords

Comments

Start with a complete bipartite graph K(6,n) with vertex sets A and B where |A| = 6 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where exactly two removed edges are incident to the same point in A and exactly two removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 6 X n matrices (with n at least 4) with three fixed zero entries where exactly two zero entries occur in one row and exactly two zero entries occur in one column, with no zero rows or columns.
Take a complete bipartite graph K(6,n) (with n at least 4) having parts A and B where |A| = 6. This sequence gives the number of edge covers of the graph obtained from this K(6,n) graph after removing three edges, where exactly two removed edges are incident to the same vertex in A and exactly two removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Programs

  • Mathematica
    Array[465*63^# - 1110*31^# + 967*15^# - 388*7^# + 70*3^# - 4 &[# - 2] &, 12, 4] (* Michael De Vlieger, May 01 2021 *)

Formula

a(n) = 465*63^(n-2) - 1110*31^(n-2) + 967*15^(n-2) - 388*7^(n-2) + 70*3^(n-2) - 4.

A340437 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(4,n) (with n at least 4) missing three edges, where exactly two of the removed edges are incident to the same vertex in the 4-point set but none of the removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

3451, 64705, 1068475, 16734721, 256041211, 3875962945, 58387463995, 877549918081, 13175419936891, 197716513589185, 2966344254717115, 44499339824298241, 667519329831422971, 10012994576066466625, 150196351045142283835, 2252955292518089539201, 33794399575693844931451
Offset: 4

Author

Rachel Wofford, Apr 02 2021

Keywords

Comments

Start with a complete bipartite graph K(4,n) with vertex sets A and B where |A| = 4 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where exactly two of the removed edges are incident to the same point in A but none of the removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 4 X n matrices (with n at least 4) with three fixed zero entries where exactly two zero entries occur in one row and no column has more than one zero entry, with no zero rows or columns.
Take a complete bipartite graph K(4,n) (with n at least 4) having parts A and B where |A| = 4. This sequence gives the number of edge covers of the graph obtained from this K(4,n) graph after removing three edges, where exactly two of the removed edges are incident to the same vertex in A but none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Programs

  • Mathematica
    LinearRecurrence[{26,-196,486,-315},{3451,64705,1068475,16734721},20] (* Harvey P. Dale, Apr 03 2022 *)

Formula

a(n) = 343*15^(n-3) - 264*7^(n-3) + 52*3^(n-3) - 2.
G.f.: x^4*(3451 - 25021*x + 62541*x^2 - 40635*x^3)/(1 - 26*x + 196*x^2 - 486*x^3 + 315*x^4). - Stefano Spezia, Apr 10 2021

A340436 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(3,n) (with n at least 4) missing three edges, where exactly two of the removed edges are incident to the same vertex in the 3-point set but none of the removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

151, 1207, 8911, 63775, 450631, 3167047, 22207231, 155564335, 1089291511, 7626064087, 53385519151, 373707845695, 2615982554791, 18311960788327, 128183974232671, 897288565771855, 6281022198832471, 43967162107115767, 307770154895675791
Offset: 4

Author

Rachel Wofford, Apr 02 2021

Keywords

Comments

Start with a complete bipartite graph K(3,n) with vertex sets A and B where |A| = 3 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where exactly two of the removed edges are incident to the same point in A but none of the removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 3 X n matrices (with n at least 4) with three fixed zero entries where exactly two zero entries occur in one row and no column has more than one zero entry, with no zero rows or columns.
Take a complete bipartite graph K(3,n) (with n at least 4) having parts A and B where |A| = 3. This sequence gives the number of edge covers of the graph obtained from this K(3,n) graph after removing three edges, where exactly two of the removed edges are incident to the same vertex in A but none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Formula

a(n) = 27*7^(n-3) - 13*3^(n-3) + 1.
G.f.: x^4*(151 - 454*x + 315*x^2)/(1 - 11*x + 31*x^2 - 21*x^3). - Stefano Spezia, Apr 10 2021

A340438 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(5,n) (with n at least 4) missing three edges, where exactly two of the removed edges are incident to the same vertex in the 5-point set but none of the removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

61567, 2542687, 89633839, 2950367599, 94105517407, 2957415542527, 92285440927759, 2869955834892559, 89105404945690687, 2764320330627851167, 85724730074633335279, 2657928686852792646319, 82402720510664595630367, 2554588306905035356179007, 79193797099779761462440399
Offset: 4

Author

Rachel Wofford, Apr 02 2021

Keywords

Comments

Start with a complete bipartite graph K(5,n) with vertex sets A and B where |A| = 5 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where exactly two of the removed edges are incident to the same point in A but none of the removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 5 X n matrices (with n at least 4) with three fixed zero entries where exactly two zero entries occur in one row and no column has more than one zero entry, with no zero rows or columns.
Take a complete bipartite graph K(5,n) (with n at least 4) having parts A and B where |A| = 5. This sequence gives the number of edge covers of the graph obtained from this K(5,n) graph after removing three edges, where exactly two of the removed edges are incident to the same vertex in A but none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Formula

a(n) = 3375*31^(n-3) - 3339*15^(n-3) + 1054*7^(n-3) - 118*3^(n-3) + 3.

A340433 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(4,n) (with n at least 4) missing three edges, where all three removed edges are incident to different vertices in the 4-point set but all three removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

2426, 43664, 709682, 11039864, 168395306, 2545615904, 38322357602, 575803142024, 8643824410586, 129704815623344, 1945904406111122, 29190891370520984, 437879647739376266, 6568308657050321984, 98525427444538818242, 1477886994795768920744
Offset: 4

Author

Rachel Wofford, Jan 07 2021

Keywords

Comments

Start with a complete bipartite graph K(4,n) with vertex sets A and B where |A| = 4 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where all three removed edges are incident to different points in A but all three removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 4 X n matrices (with n at least 4) with three fixed zero entries all of which are in the same column with no zero rows or columns.
Take a complete bipartite graph K(4,n) (with n at least 4) having parts A and B where |A| = 4. This sequence gives the number of edge covers of the graph obtained from this K(4,n) graph after removing three edges, where the removed edges are incident to different vertices in A and none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Formula

a(n) = 15^(n-1) - 3*7^(n-1) + 3^(n) - 1.
From Stefano Spezia, Jan 07 2021: (Start)
G.f.: 2*x^4*(1213 - 9706*x + 24957*x^2 - 16380*x^3)/(1 - 26*x + 196*x^2 - 486*x^3 + 315*x^4).
a(n) = 26*a(n-1) - 196*a(n-2) + 486*a(n-3) - 315*a(n-4) for n > 7. (End)

A340435 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(6,n) (with n at least 4) missing three edges, where all three removed edges are incident to different vertices in the 6-point set but all three removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

1014458, 85045184, 6126191066, 411615281120, 26756164505978, 1711634190402944, 108645469309633946, 6869952591587660960, 433592445465504586298, 27340695032306205303104, 1723219625722022031240026, 108586272500880714880450400, 6841661762270647247773447418
Offset: 4

Author

Rachel Wofford, Jan 07 2021

Keywords

Comments

Start with a complete bipartite graph K(6,n) with vertex sets A and B where |A| = 6 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where all three removed edges are incident to different points in A but all three removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 6 X n matrices (with n at least 4) with three fixed zero entries all of which are in the same column with no zero rows or columns.
Take a complete bipartite graph K(6,n) (with n at least 4) having parts A and B where |A| = 6. This sequence gives the number of edge covers of the graph obtained from this K(6,n) graph after removing three edges, where the removed edges are incident to different vertices in A and none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Formula

a(n) = 7*63^(n-1) - 30*31^(n-1) + 51*15^(n-1) - 43*7^(n-1) + 6*3^(n) - 3.

A340434 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(5,n) (with n at least 4) missing three edges, where all three removed edges are incident to different vertices in the 5-point set but all three removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

57152, 2248976, 77784248, 2538972344, 80670722672, 2530567728416, 78896594655848, 2452545943242824, 76130313033068192, 2361561349263377456, 73231232199903981848, 2270510693649412710104, 70390969213953161845712, 2182197113248136520812096, 67649266538598993456642248
Offset: 4

Author

Rachel Wofford, Jan 07 2021

Keywords

Comments

Start with a complete bipartite graph K(5,n) with vertex sets A and B where |A| = 5 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where all three removed edges are incident to different points in A but all three removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 5 X n matrices (with n at least 4) with three fixed zero entries all of which are in the same column with no zero rows or columns.
Take a complete bipartite graph K(5,n) (with n at least 4) having parts A and B where |A| = 5. This sequence gives the number of edge covers of the graph obtained from this K(5,n) graph after removing three edges, where the removed edges are incident to different vertices in A and none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Formula

a(n) = 3*31^(n-1) - 11*15^(n-1) + 15*7^(n-1) - 3^(n+1) + 2.

A340405 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(6,n) (with n at least 4) missing three edges, where the removed edges are incident to different vertices in the 6-point set and none of the removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

1084508, 91075250, 6565114436, 441241902314, 28686096681068, 1835221289891810, 116494017052053716, 7366358270603987354, 464926482693459729788, 29316615999089974986770, 1847760848280105290960996, 116434174169077299044440394, 7336135517363636128979098508
Offset: 4

Author

Rachel Wofford, Jan 06 2021

Keywords

Comments

Start with a complete bipartite graph K(6,n) with vertex sets A and B where |A| = 6 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where the removed edges are incident to different points in A and none of the removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 6 X n matrices with three fixed zero entries none of which are in the same row or column with no zero rows or columns.
Take a complete bipartite graph K(6,n) (with n at least 4) having parts A and B where |A| = 6. This sequence gives the number of edge covers of the graph obtained from this K(6,n) graph after removing three edges, where the removed edges are incident to different vertices in A and none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Formula

a(n) = 29791*63^(n-3) - 31050*31^(n-3) + 12369*15^(n-3) - 2260*7^(n-3) + 19*3^(n-1) - 3.
From Alejandro J. Becerra Jr., Feb 13 2021: (Start)
G.f.: -2*x^4*(2773914255*x^5 - 4404958866*x^4 + 1920200130*x^3 - 308614840*x^2 + 19532855*x - 542254)/((1 - x)*(1 - 3*x)*(1 - 7*x)*(1 - 15*x)*(1 - 31*x)*(1 - 63*x)).
a(n) = 120*a(n-1) - 4593*a(n-2) + 69688*a(n-3) - 428787*a(n-4) + 978768*a(n-5) - 615195*a(n-6). (End)

A340404 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(5,n) (with n at least 4) missing three edges, where the removed edges are incident to different vertices in the 5-point set and none of the removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

66914, 2633546, 91075250, 2972550458, 94442228354, 2962494091946, 92361814692050, 2871102810997658, 89122619177691554, 2764578611249652746, 85728604753979332850, 2657986810333194788858, 82403592385902351106754, 2554601385194824465949546
Offset: 4

Author

Rachel Wofford, Jan 06 2021

Keywords

Comments

Start with a complete bipartite graph K(5,n) with vertex sets A and B where |A| = 5 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where the removed edges are incident to different points in A and none of the removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 5 X n matrices with three fixed zero entries none of which are in the same row or column with no zero rows or columns.
Take a complete bipartite graph K(5,n) (with n at least 4) having parts A and B where |A| = 5. This sequence gives the number of edge covers of the graph obtained from this K(5,n) graph after removing three edges, where the removed edges are incident to different vertices in A and none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Formula

a(n) = 3375*31^(n-3) - 2891*15^(n-3) + 846*7^(n-3) - 10*3^(n-1) + 2.
From Alejandro J. Becerra Jr., Feb 13 2021: (Start)
G.f.: 2*x^4*(6064065*x^4 - 9507684*x^3 + 4005478*x^2 - 590276*x + 33457)/((1 - x)*(1 - 3*x)*(1 - 7*x)*(1 - 15*x)*(1 - 31*x)).
a(n) = 57*a(n-1) - 1002*a(n-2) + 6562*a(n-3) - 15381*a(n-4) + 9765*a(n-5). (End)

A340403 Number of sets in the geometry determined by the Hausdorff metric at each location between two sets defined by a complete bipartite graph K(4,n) (with n at least 4) missing three edges, where the removed edges are incident to different vertices in the 4-point set and none of the removed edges are incident to the same vertex in the other set.

Original entry on oeis.org

3740, 66914, 1084508, 16848674, 256844060, 3881598434, 58426959068, 877826523554, 13177356595100, 197730071456354, 2966439163566428, 44500004197580834, 667523980478413340, 10013027130697435874, 150196578927865178588, 2252956887698068132514
Offset: 4

Author

Rachel Wofford, Jan 06 2021

Keywords

Comments

Start with a complete bipartite graph K(4,n) with vertex sets A and B where |A| = 4 and |B| is at least 4. We can arrange the points in sets A and B such that h(A,B) = d(a,b) for all a in A and b in B, where h is the Hausdorff metric. The pair [A,B] is a configuration. Then a set C is between A and B at location s if h(A,C) = h(C,B) = h(A,B) and h(A,C) = s. Call a pair ab, where a is in A and b is in B an edge. This sequence provides the number of sets between sets A' and B' at location s in a new configuration [A',B'] obtained from [A,B] by removing three edges, where the removed edges are incident to different points in A and none of the removed edges are incident to the same point in B. So this sequence tells the number of sets at each location on the line segment between A' and B'.
Number of {0,1} 4 X n matrices (with n at least 4) with three fixed zero entries none of which are in the same row or column with no zero rows or columns.
Take a complete bipartite graph K(4,n) (with n at least 4) having parts A and B where |A| = 4. This sequence gives the number of edge covers of the graph obtained from this K(4,n) graph after removing three edges, where the removed edges are incident to different vertices in A and none of the removed edges are incident to the same vertex in B.

Crossrefs

Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.

Programs

  • Mathematica
    LinearRecurrence[{26,-196,486,-315},{3740,66914,1084508,16848674},20] (* Harvey P. Dale, Sep 18 2021 *)

Formula

a(n) = 343*15^(n-3) - 216*7^(n-3) + 4*3^(n-1) - 1.
From Stefano Spezia, Jan 06 2021: (Start)
G.f.: 2*x^4*(1870 - 15163*x + 38892*x^2 - 25515*x^3)/(1 - 26*x + 196*x^2 - 486*x^3 + 315*x^4).
a(n) = 26*a(n-1) - 196*a(n-2) + 486*a(n-3) - 315*a(n-4) for n > 7. (End)