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.

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A068600 Number of n-uniform tilings having n different arrangements of polygons about their vertices.

Original entry on oeis.org

11, 20, 39, 33, 15, 10, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Brian Galebach, Mar 28 2002

Keywords

Comments

Sequence gives the number of edge-to-edge regular-polygon tilings having n topologically distinct vertex types, with each vertex type having a different arrangement of surrounding polygons. Does not allow for tilings with two or more vertex types having the same arrangement of surrounding polygons, even when those vertices are topologically distinct. There are no 8- or higher-uniform tilings having the equivalent number of distinct polygon arrangements.
There are eleven 1-uniform tilings (also called the "Archimedean" tessellations) which comprise the three regular tessellations (all triangles, squares, or hexagons) plus the eight semiregular tessellations. (See A250120. - N. J. A. Sloane, Nov 29 2014)

References

  • This sequence was originally calculated by Otto Krotenheerdt.
  • Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, page 69.
  • Krotenheerdt, Otto. "Die homogenen Mosaike n-ter Ordnung in der euklidischen Ebene," Wiss. Z. Martin-Luther-Univ. Halle-Wittenberg. Math.-natur. Reihe, 18(1969), 273-290; 19 (1970)19-38 and 97-122.

Crossrefs

Cf. A068599.
List of coordination sequences for uniform planar nets: A008458 (the planar net 3.3.3.3.3.3), A008486 (6^3), A008574 (4.4.4.4 and 3.4.6.4), A008576 (4.8.8), A008579 (3.6.3.6), A008706 (3.3.3.4.4), A072154 (4.6.12), A219529 (3.3.4.3.4), A250120(3.3.3.3.6), A250122 (3.12.12).

A101853 a(n) = n*(20 + 15*n + n^2)/6.

Original entry on oeis.org

6, 18, 37, 64, 100, 146, 203, 272, 354, 450, 561, 688, 832, 994, 1175, 1376, 1598, 1842, 2109, 2400, 2716, 3058, 3427, 3824, 4250, 4706, 5193, 5712, 6264, 6850, 7471, 8128, 8822, 9554, 10325, 11136, 11988, 12882, 13819, 14800
Offset: 1

Views

Author

Cecilia Rossiter (cecilia(AT)noticingnumbers.net), Dec 18 2004

Keywords

Comments

4th partial summation within series as series accumulate n times from an initial sequence of Euler Triangle's row 3: 1,4,1. The 1,4,1 is the left column, A101101 the second column, A008458 the third, A003215 the fourth column etc of the array in the example. a(n) is the 4th row.

Examples

			Left column the third row of A008292, and subsequent columns defined as partial sums along their preceding neighbors:
1 1  1   1   1    1    1     1     1     1     1
4 5  6   7   8    9   10    11    12    13    14
1 6 12  19  27   36   46    57    69    82    96  A051936
0 6 18  37  64  100  146   203   272   354   450  A101853
0 6 24  61 125  225  371   574   846  1200  1650  A101854
0 6 30  91 216  441  812  1386  2232  3432  5082  A101855
0 6 36 127 343  784 1596  2982  5214  8646 13728
0 6 42 169 512 1296 2892  5874 11088 19734 33462
0 6 48 217 729 2025 4917 10791 21879 41613 75075
...
		

Crossrefs

Row n=3 of A255961.

Programs

  • Magma
    I:=[6, 18, 37, 64]; [n le 4 select I[n] else 4*Self(n-1)-6*Self(n-2)+4*Self(n-3)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Jun 26 2012
    
  • Mathematica
    LinearRecurrence[{4,-6,4,-1},{6,18,37,64},40] (* or *) CoefficientList[Series[(6-6*x+x^2)/(x-1)^4,{x,0,40}],x] (* Vincenzo Librandi, Jun 26 2012 *)
  • PARI
    a(n)=n*(20+15*n+n^2)/6 \\ Charles R Greathouse IV, Oct 16 2015

Formula

G.f.: x*(6 - 6*x + x^2)/(x - 1)^4. - R. J. Mathar, Dec 06 2011
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). - Vincenzo Librandi, Jun 26 2012
E.g.f.: exp(x)*x*(36 + 18*x + x^2)/6. - Stefano Spezia, Oct 14 2022

A250123 Coordination sequence of point of type 3.3.4.3.4 in 4-uniform tiling {3.3.4.3.4; 3.3.4.12; 3.3.12.4; 3.4.3.12}.

Original entry on oeis.org

1, 5, 8, 8, 11, 17, 25, 27, 24, 30, 38, 46, 47, 44, 46, 50, 64, 68, 65, 66, 70, 80, 80, 83, 87, 91, 100, 100, 99, 99, 109, 121, 121, 119, 119, 125, 133, 139, 140, 140, 145, 153, 155, 152, 158, 166, 174, 175, 172, 174, 178, 192, 196, 193, 194, 198, 208, 208, 211
Offset: 0

Views

Author

N. J. A. Sloane, Nov 29 2014

Keywords

Comments

This tiling appears as an example in Connelly et al. (2014), Fig. 6 (the heavy black lines in the figures here are an artifact from that figure).
For the definition of k-uniform tiling see Section 2.2 of Chapter 2 of Grünbaum and Shephard (1987).

References

  • Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987.

Crossrefs

List of coordination sequences for uniform planar nets: A008458 (the planar net 3.3.3.3.3.3), A008486 (6^3), A008574 (4.4.4.4 and 3.4.6.4), A008576 (4.8.8), A008579 (3.6.3.6), A008706(3.3.3.4.4), A072154 (4.6.12), A219529 (3.3.4.3.4), A250120 (3.3.3.3.6), A250122 (3.12.12).

Formula

Empirical g.f.: -(x+1)*(x^15 +3*x^14 -4*x^11 -6*x^10 -7*x^9 -4*x^8 -7*x^7 -11*x^6 -9*x^5 -7*x^4 -4*x^3 -4*x^2 -4*x -1) / ((x -1)^2*(x^4 +x^3 +x^2 +x +1)*(x^6 +x^5 +x^4 +x^3 +x^2 +x +1)). - Colin Barker, Dec 02 2014

Extensions

Galebach link from Joseph Myers, Nov 30 2014
Extended by Joseph Myers, Dec 02 2014

A250124 Coordination sequence of point of type 3.3.12.4 in 4-uniform tiling {3.3.4.3.4; 3.3.4.12; 3.3.12.4; 3.4.3.12}.

Original entry on oeis.org

1, 4, 7, 10, 15, 16, 21, 29, 28, 34, 33, 40, 48, 45, 53, 51, 59, 65, 64, 72, 68, 78, 83, 83, 89, 87, 97, 100, 102, 107, 106, 114, 119, 121, 124, 125, 132, 138, 138, 143, 144, 149, 157, 156, 162, 161, 168, 176, 173, 181, 179, 187, 193, 192, 200, 196, 206, 211, 211
Offset: 0

Views

Author

N. J. A. Sloane, Nov 29 2014

Keywords

Comments

This tiling appears as an example in Connelly et al. (2014), Fig. 6 (the heavy black lines in the figures here are an artifact from that figure).
For the definition of k-uniform tiling see Section 2.2 of Chapter 2 of Grünbaum and Shephard (1987).

References

  • Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987.

Crossrefs

List of coordination sequences for uniform planar nets: A008458 (the planar net 3.3.3.3.3.3), A008486 (6^3), A008574 (4.4.4.4 and 3.4.6.4), A008576 (4.8.8), A008579 (3.6.3.6), A008706(3.3.3.4.4), A072154 (4.6.12), A219529 (3.3.4.3.4), A250120 (3.3.3.3.6), A250122 (3.12.12).

Formula

Empirical g.f.: -(3*x^14 -4*x^12 -4*x^11 -7*x^10 -12*x^9 -14*x^8 -21*x^7 -17*x^6 -15*x^5 -15*x^4 -10*x^3 -7*x^2 -4*x -1) / ((x -1)^2*(x^4 +x^3 +x^2 +x +1)*(x^6 +x^5 +x^4 +x^3 +x^2 +x +1)). - Colin Barker, Dec 02 2014

Extensions

Galebach link from Joseph Myers, Nov 30 2014
Extended by Joseph Myers, Dec 02 2014

A250125 Coordination sequence of point of type 3.4.3.12 in 4-uniform tiling {3.3.4.3.4; 3.3.4.12; 3.3.12.4; 3.4.3.12}.

Original entry on oeis.org

1, 4, 6, 11, 13, 15, 23, 23, 33, 30, 33, 42, 41, 54, 46, 54, 58, 58, 73, 64, 75, 74, 79, 89, 81, 94, 92, 100, 105, 102, 110, 109, 119, 123, 123, 126, 130, 135, 140, 142, 144, 151, 151, 161, 158, 161, 170, 169, 182, 174, 182, 186, 186, 201, 192, 203, 202, 207, 217
Offset: 0

Views

Author

N. J. A. Sloane, Nov 29 2014

Keywords

Comments

This tiling appears as an example in Connelly et al. (2014), Fig. 6 (the heavy black lines in the figures here are an artifact from that figure).
For the definition of k-uniform tiling see Section 2.2 of Chapter 2 of Grünbaum and Shephard (1987).

References

  • Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987.

Crossrefs

List of coordination sequences for uniform planar nets: A008458 (the planar net 3.3.3.3.3.3), A008486 (6^3), A008574 (4.4.4.4 and 3.4.6.4), A008576 (4.8.8), A008579 (3.6.3.6), A008706(3.3.3.4.4), A072154 (4.6.12), A219529 (3.3.4.3.4), A250120 (3.3.3.3.6), A250122 (3.12.12).

Formula

Empirical g.f.: -(x^17 +x^16 +x^15 +x^14 -2*x^13 -4*x^12 -6*x^11 -7*x^10 -11*x^9 -18*x^8 -16*x^7 -19*x^6 -14*x^5 -13*x^4 -11*x^3 -6*x^2 -4*x -1) / ((x -1)^2*(x^4 +x^3 +x^2 +x +1)*(x^6 +x^5 +x^4 +x^3 +x^2 +x +1)). - Colin Barker, Dec 02 2014

Extensions

Galebach link from Joseph Myers, Nov 30 2014
Extended by Joseph Myers, Dec 02 2014

A250126 Coordination sequence of point of type 3.3.4.12 in 4-uniform tiling {3.3.4.3.4; 3.3.4.12; 3.3.12.4; 3.4.3.12}.

Original entry on oeis.org

1, 4, 9, 9, 12, 19, 21, 28, 27, 31, 38, 40, 48, 44, 49, 56, 57, 67, 63, 69, 73, 75, 85, 80, 88, 92, 95, 102, 98, 106, 109, 114, 121, 118, 123, 127, 132, 138, 137, 142, 147, 149, 156, 155, 159, 166, 168, 176, 172, 177, 184, 185, 195, 191, 197, 201, 203, 213, 208
Offset: 0

Views

Author

N. J. A. Sloane, Nov 29 2014

Keywords

Comments

This tiling appears as an example in Connelly et al. (2014), Fig. 6 (the heavy black lines in the figures here are an artifact from that figure).
For the definition of k-uniform tiling see Section 2.2 of Chapter 2 of Grünbaum and Shephard (1987).

References

  • Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987.

Crossrefs

List of coordination sequences for uniform planar nets: A008458 (the planar net 3.3.3.3.3.3), A008486 (6^3), A008574 (4.4.4.4 and 3.4.6.4), A008576 (4.8.8), A008579 (3.6.3.6), A008706(3.3.3.4.4), A072154 (4.6.12), A219529 (3.3.4.3.4), A250120 (3.3.3.3.6), A250122 (3.12.12).

Formula

Empirical g.f.: -(2*x^16 +x^14 -2*x^12 -7*x^11 -10*x^10 -10*x^9 -14*x^8 -18*x^7 -17*x^6 -18*x^5 -12*x^4 -9*x^3 -9*x^2 -4*x -1) / ((x -1)^2*(x^4 +x^3 +x^2 +x +1)*(x^6 +x^5 +x^4 +x^3 +x^2 +x +1)). - Colin Barker, Dec 02 2014

Extensions

Galebach link from Joseph Myers, Nov 30 2014
Extended by Joseph Myers, Dec 02 2014

A182618 Number of new grid points that are covered by the toothpicks added at n-th-stage to the toothpick spiral of A182617.

Original entry on oeis.org

6, 4, 3, 3, 3, 3, 2, 3, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3
Offset: 1

Views

Author

Omar E. Pol, Dec 12 2010

Keywords

Comments

In the toothpick spiral the toothpicks are connected by their endpoints. See A182617 for more information.
Attempt at an explanation, R. J. Mathar, Dec 13 2010: (Start)
In the hexagonal grid, we can pick any of the hexagons as a center, and then define a ring of 6 first neighbors (hexagons adjacent to the center), then define a ring of 12 second neighbors (hexagons adjacent to any of the first ring) and so on. The current sequence describes a self-avoiding walk which starts in a spiral around the center hexagon, which covers 5 edges. The walk then takes one step to reach the rim of the first ring and travels once around this ring until it reaches a point where self-avoidance stops it. It then takes one step to reach the rim of the second ring and walks around that one, etc. Imagine that on each edge we place a toothpick if it's on the path, and interrupt counting the total number of toothpicks each time one of the hexagons has six vertices covered. The first differences of these intermediate totals define the sequence. (End)

Examples

			At stage 1, starting from a node on the hexagonal net, we place 5 toothpicks on 5 edges of the first hexagon, so a(1)= 6 because there are 6 grid points that are covered by the toothpicks.
At stage 2, starting from the last exposed endpoints, we place 4 toothpicks on the edges of the second hexagon, so a(2)=4 because there are new 4 grid points that are covered by the toothpicks.
At stage 3, starting from the last exposed endpoints we place 3 toothpicks on the edges of the third hexagon, so a(3)=3 because there are new 3 grid points covered. Etc.
If written as a triangle, begins:
6,
4,3,3,3,3,2,
3,3,2,3,2,3,2,3,2,3,2,2,
3,2,3,2,2,3,2,2,3,2,2,3,2,2,3,2,2,2,
3,2,2,3,2,2,2,3,2,2,2,3,2,2,2,3,2,2,2,3,2,2,2,2,
3,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,2
		

Crossrefs

Row n has A008458(n-1) terms. Row sums give A017593.

A182619 Number of vertices that are connected to two edges in a spiral without holes constructed with n hexagons.

Original entry on oeis.org

6, 8, 9, 10, 11, 12, 12, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 18, 19, 19, 20, 20, 20, 21, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 24, 24
Offset: 1

Views

Author

Omar E. Pol, Dec 13 2010

Keywords

Comments

The structure shows a hexagonal growth as in A182618.
a(n) is the number of vertices of the convex parts of the perimeter of the structure.
This sequence can be constructed geometrically in the following manner: Construct a gapless array of n equal circles with the rule of always choosing an arrangement with the maximum number of completely enclosed inner circles. Then, a(n) equals the number of circles required to create a kissing perimeter around the original array. Examples: a(1) = 6 because it takes 6 circles to create a kissing perimeter around 1 circle. a(7) = 12 because it takes 12 circles to create a kissing perimeter around 7 circles, which are arranged with 1 circle in center surrounded by 6 kissing circles. One could describe this as the "kissing numbers of kissing circles" sequence. - Peter Woodward, Apr 25 2015
a(n) is also the size of the smallest hexagonal polyomino that admits a hole of size n (Cf. A257594). - Luca Petrone, Feb 28 2017

Examples

			For n=1 there is 1 hexagon, so a(1)= 6 because there are 6 vertices that are connected to two edges.
For n=2 there are 2 connected hexagons, so a(2)= 8 because there are 8 vertices that are connected to two edges.
For n=3 there are 3 connected hexagons, so a(3)= 9 because there are 9 vertices that are connected to two edges.
If written as a triangle, begins:
6,
8,9,10,11,12,12,
13,14,14,15,15,16,16,17,17,18,18,18,
19,19,20,20,20,21,21,21,22,22,22,23,23,23,24,24,24,24
		

Crossrefs

Row n has A008458(n-1) terms.

A354957 Coordination sequence for the Manhattan hexagonal lattice with respect to the origin.

Original entry on oeis.org

1, 3, 7, 14, 21, 25, 35, 35, 49, 45, 63, 55, 77, 65, 91, 75, 105, 85, 119, 95, 133, 105, 147, 115, 161, 125, 175, 135, 189, 145, 203, 155, 217, 165, 231, 175, 245, 185, 259, 195, 273, 205, 287, 215, 301, 225, 315, 235, 329, 245, 343, 255, 357, 265, 371, 275
Offset: 0

Views

Author

Rémy Sigrist, Jun 13 2022

Keywords

Comments

In the Manhattan hexagonal lattice, streets parallel to one of the 3 axis have alternating orientations:
Z Y
.---<---.
/ \ / \
v ^ ^ v
/ \ / \
.--->---O--->---. X
\ / \ /
v ^ ^ v
\ / \ /
.---<---.

Crossrefs

Programs

  • PARI
    See Links section.

A086460 Square array read by antidiagonals: T(n,k)=nk+0^n.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 4, 3, 0, 1, 4, 6, 6, 4, 0, 1, 5, 8, 9, 8, 5, 0, 1, 6, 10, 12, 12, 10, 6, 0, 1, 7, 12, 15, 16, 15, 12, 7, 0, 1, 8, 14, 18, 20, 20, 18, 14, 8, 0, 1, 9, 16, 21, 24, 25, 24, 21, 16, 9, 0, 1, 10, 18, 24, 28, 30, 30, 28, 24, 18, 10, 0, 1, 11, 20, 27, 32, 35, 36
Offset: 0

Views

Author

Paul Barry, Jul 21 2003

Keywords

Comments

Rows include A028310, A004277, A008486, A008574, A008706, A008458. Main diagonal is n^2+0^n (A000290, preceded by extra 1). Inverse binomial transform of array A049513.

Examples

			Rows begin
1 0 0 0 0 ...
1 1 2 3 4 ...
1 2 4 6 8 ...
1 3 6 9 12 ...
1 4 8 12 16 ...
		

Formula

T(n, k)=nk+0^n
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