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.

Showing 1-9 of 9 results.

A293961 Number T(n,k) of linear chord diagrams having n chords and maximal chord length k (or k=0 if n=0); triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 2, 0, 1, 4, 10, 0, 1, 10, 24, 70, 0, 1, 20, 82, 212, 630, 0, 1, 42, 300, 798, 2324, 6930, 0, 1, 84, 894, 3800, 10078, 30188, 90090, 0, 1, 170, 2744, 18186, 51804, 150046, 452724, 1351350, 0, 1, 340, 8594, 71624, 313006, 851692, 2545390, 7695828, 22972950
Offset: 0

Views

Author

Alois P. Heinz, Oct 20 2017

Keywords

Comments

All terms in columns k > 1 are even.

Examples

			Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1,   2;
  0, 1,   4,   10;
  0, 1,  10,   24,    70;
  0, 1,  20,   82,   212,   630;
  0, 1,  42,  300,   798,  2324,   6930;
  0, 1,  84,  894,  3800, 10078,  30188,  90090;
  0, 1, 170, 2744, 18186, 51804, 150046, 452724, 1351350;
  ...
		

Crossrefs

Columns k=0-2 give: A000007, A057427, A167030(n+1).
Row sums give A001147.
Main diagonal gives A293962.
T(2n,n) gives A293963.

Formula

A(n,k) = A293960(n,k) - A293960(n,k-1) for k>0, A(n,0) = A000007(n).

A293995 Number of linear chord diagrams having n chords and no chord length larger than three.

Original entry on oeis.org

1, 1, 3, 15, 35, 103, 343, 979, 2915, 8935, 26559, 79499, 239547, 717455, 2151095, 6459027, 19371507, 58106071, 174349295, 523022555, 1569013931, 4707208351, 14121515303, 42364215075, 127093528675, 381280144743, 1143838446943, 3431519977579, 10294558387995
Offset: 0

Views

Author

Alois P. Heinz, Oct 21 2017

Keywords

Crossrefs

Column k=3 of A293960.

Programs

  • Mathematica
    LinearRecurrence[{2,1,8,-6},{1,1,3,15},30] (* Harvey P. Dale, Aug 08 2021 *)

Formula

G.f.: -(x-1)/((3*x-1)*(2*x^3-2*x^2-x-1)).

A293996 Number of linear chord diagrams having n chords and no chord length larger than four.

Original entry on oeis.org

1, 1, 3, 15, 105, 315, 1141, 4779, 21101, 80559, 314185, 1267551, 5160933, 20504123, 81554685, 326682775, 1310978305, 5239019143, 20931551661, 83743554723, 335175239813, 1340542340399, 5360923216953, 21444223178271, 85786427569333, 343141430067947
Offset: 0

Views

Author

Alois P. Heinz, Oct 21 2017

Keywords

Crossrefs

Column k=4 of A293960.

Formula

G.f.: -(2*x^4+4*x^3+x^2+x-1) / ((4*x-1) * (12*x^7+30*x^6+14*x^5+8*x^4-13*x^3 -6*x^2 -2*x-1)).

A293997 Number of linear chord diagrams having n chords and no chord length larger than five.

Original entry on oeis.org

1, 1, 3, 15, 105, 945, 3465, 14857, 72905, 393565, 2152693, 10317169, 49808117, 247455873, 1256019673, 6371895677, 31696702545, 157383838325, 785587613797, 3938599251649, 19742522444733, 98655068282297, 492637126850897, 2462204077446773, 12316715419452585
Offset: 0

Views

Author

Alois P. Heinz, Oct 21 2017

Keywords

Crossrefs

Column k=5 of A293960.

Programs

  • Mathematica
    CoefficientList[Series[-(24x^11-84x^10+76x^9+20x^8-10x^7-90x^6+12x^5+35x^4+4x^2+2x-1)/((5x-1)(576x^15-2016x^14+1584x^13+744x^12+ 456x^11- 2824x^10-380x^9+ 1058x^8+ 170x^7+352x^6+200x^5-59x^4-28x^3-6x^2-2x-1)),{x,0,30}],x] (* or *) LinearRecurrence[ {3,4,2,81,495,-648,-1590,208,-5670,-924,14576,-1536,-2136,-9936,10656,-2880},{1,1,3,15,105,945,3465,14857,72905,393565,2152693,10317169,49808117,247455873,1256019673,6371895677},30] (* Harvey P. Dale, Jan 03 2024 *)

Formula

G.f.: -(24*x^11-84*x^10+76*x^9+20*x^8-10*x^7-90*x^6+12*x^5+35*x^4+4*x^2+2*x-1) / ((5*x-1) *(576*x^15 -2016*x^14 +1584*x^13 +744*x^12 +456*x^11 -2824*x^10 -380*x^9 +1058*x^8 +170*x^7 +352*x^6 +200*x^5 -59*x^4 -28*x^3 -6*x^2 -2*x-1)).

A293998 Number of linear chord diagrams having n chords and no chord length larger than six.

Original entry on oeis.org

1, 1, 3, 15, 105, 945, 10395, 45045, 222951, 1245257, 7689707, 50548041, 328681355, 1898148921, 10938090235, 64447508901, 388656309623, 2372510073525, 14406809496311, 86092382481933, 512757617989667, 3064484085534721, 18400499270245971, 110741448251269561
Offset: 0

Views

Author

Alois P. Heinz, Oct 21 2017

Keywords

Crossrefs

Column k=6 of A293960.

A293999 Number of linear chord diagrams having n chords and no chord length larger than seven.

Original entry on oeis.org

1, 1, 3, 15, 105, 945, 10395, 135135, 675675, 3790647, 23694083, 162961399, 1209395171, 9332799283, 70178707279, 474578729935, 3181796735723, 21683288205723, 150990425051331, 1069361164106091, 7617764489275535, 53863160510249543, 375786310609620379
Offset: 0

Views

Author

Alois P. Heinz, Oct 21 2017

Keywords

Crossrefs

Column k=7 of A293960.

A294000 Number of linear chord diagrams having n chords and no chord length larger than eight.

Original entry on oeis.org

1, 1, 3, 15, 105, 945, 10395, 135135, 2027025, 11486475, 72025173, 497809599, 3759823201, 30676852011, 265149012989, 2341915514787, 19966886272757, 154807536575931, 1184739742163293, 9169888620679203, 72323378114077925, 580752883543676927, 4717664674505952353
Offset: 0

Views

Author

Alois P. Heinz, Oct 21 2017

Keywords

Crossrefs

Column k=8 of A293960.

A294001 Number of linear chord diagrams having n chords and no chord length larger than nine.

Original entry on oeis.org

1, 1, 3, 15, 105, 945, 10395, 135135, 2027025, 34459425, 218243025, 1512548793, 11451456921, 94099903993, 832822929881, 7850100744697, 77247769844585, 766602148661941, 7301487795390325, 63860693057569633, 549669975975395633, 4765146317902742829
Offset: 0

Views

Author

Alois P. Heinz, Oct 21 2017

Keywords

Crossrefs

Column k=9 of A293960.

A294002 Number of linear chord diagrams having n chords and no chord length larger than ten.

Original entry on oeis.org

1, 1, 3, 15, 105, 945, 10395, 135135, 2027025, 34459425, 654729075, 4583103525, 34788783519, 286302699633, 2541730502259, 24202811629589, 245427373661087, 2620070906538825, 28854865779691475, 317259847008270825, 3336850194636528659, 32503486859882091945
Offset: 0

Views

Author

Alois P. Heinz, Oct 21 2017

Keywords

Crossrefs

Column k=10 of A293960.
Showing 1-9 of 9 results.