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 1-6 of 6 results.

A361361 Triangle read by rows: T(n,k) is the number of bicolored cubic graphs on 2n unlabeled vertices with k vertices of the first color, n >= 0, 0 <= k <= 2*n.

Original entry on oeis.org

1, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 5, 5, 5, 2, 2, 6, 11, 33, 48, 66, 48, 33, 11, 6, 21, 68, 257, 556, 950, 1071, 950, 556, 257, 68, 21, 94, 510, 2443, 7126, 15393, 23644, 27606, 23644, 15393, 7126, 2443, 510, 94, 540, 4712, 27682, 102122, 270957, 526783, 781292, 887305, 781292, 526783, 270957, 102122, 27682, 4712, 540
Offset: 0

Views

Author

Andrew Howroyd, Mar 10 2023

Keywords

Comments

Adjacent vertices may have the same color.

Examples

			Triangle begins:
  1
  0,   0,  0;
  1,   1,  1,    1,   1;
  2,   2,  5,    5,   5,    2,   2;
  6,  11, 33,   48,  66,   48,  33,  11,   6;
  21, 68, 257, 556, 950, 1071, 950, 556, 257, 68, 21;
  ...
		

Crossrefs

Columns k=0..2 are A005638, A361410, A361411.
Row sums are A361362.
Central coefficients are A361409.
Cf. A321304 (connected), A361404.

A361407 Number of connected cubic graphs on 2n unlabeled vertices rooted at a vertex.

Original entry on oeis.org

0, 1, 2, 10, 64, 490, 4595, 51063, 657623, 9592204, 155630924, 2771922417, 53673859357, 1121581872170, 25143397213226, 601751140758134, 15310778492310274, 412656423154230159, 11743600063060974656, 351882591907696156959
Offset: 1

Views

Author

Andrew Howroyd, Mar 11 2023

Keywords

Crossrefs

Column k=1 of A321304.

Formula

G.f.: B(x)/C(x) where B(x) is the g.f. of A361410 and C(x) is the g.f. of A005638.

A361408 Number of connected cubic graphs on 2n unlabeled vertices rooted at a pair of indistinguishable vertices.

Original entry on oeis.org

0, 1, 5, 31, 248, 2382, 27233, 359800, 5364193, 88622485, 1602171855, 31410476113, 663240471075, 15001046054183, 361775504849332, 9266474332849318, 251217335356943672, 7186461542458525108, 216332059500870350414, 6835872042063656823802
Offset: 1

Views

Author

Andrew Howroyd, Mar 11 2023

Keywords

Crossrefs

Column k=2 of A321304.

Formula

G.f.: B(x)/C(x) - (D(x) + D(x^2))/2 where B(x), C(x) and D(x) are the g.f.s of A361411, A005638 and A361407, respectively.

A321305 Triangle T(n,f): the number of signed cubic graphs on 2n vertices with f edges of the first sign.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 2, 3, 2, 1, 1, 2, 3, 8, 16, 21, 21, 16, 8, 3, 2, 5, 14, 57, 152, 313, 474, 551, 474, 313, 152, 57, 14, 5, 19, 91, 491, 1806, 5034, 10604, 17318, 22033, 22033, 17318, 10604, 5034, 1806, 491, 91, 19, 85, 706, 4981, 23791, 84575, 229078, 487020, 825127, 1127783, 1250632, 1127783, 825127, 487020, 229078, 84575, 23791, 4981, 706, 85
Offset: 0

Views

Author

R. J. Mathar, Nov 03 2018

Keywords

Comments

These are connected, undirected, simple cubic graphs where each edge is signed as either "+" or "-". Row n has 1+3n entries, 0<=f<=3n. The column f=0 (1, 0, 1, 2, 5,...) counts the cubic graphs (A002851). The column f=1 (0, 1, 3, 14, 91, 706,...) counts the edge-rooted cubic graphs.

Examples

			The triangle starts:
0 vertices: 1
2 vertices: 0,0,0,0
4 vertices: 1,1,2,3,2,1,1
6 vertices: 2,3,8,16,21,21,16,8,3,2
8 vertices: 5,14,57,152,313,474,551,474,313,152,57,14,5
10 vertices: 19,91,491,1806,5034,10604,17318,22033,22033,17318,10604,5034,1806,491,91,19
		

Crossrefs

Cf. A002851 (first column), A321304 (signed vertices), A302939 (signed trees).

Formula

T(n,f) = T(n,3*n-f).

A361403 Number of bicolored connected cubic graphs on 2n unlabeled vertices.

Original entry on oeis.org

1, 0, 5, 23, 247, 4660, 124480, 4286155, 177173770, 8460721770, 456369771864, 27394102475517, 1809905002448020, 130479709461582679, 10191059146232826353, 857183200472049855001, 77244717697104310952411, 7424434373914632379955822, 758150225111024064264853603, 81967014740890327829104517614, 9353488650500180241693235592248
Offset: 0

Views

Author

Andrew Howroyd, Mar 10 2023

Keywords

Comments

Adjacent vertices may have the same color.

Crossrefs

Row sums of A321304.
Cf. A361362 (not necessarily connected).

Formula

Inverse Euler transform of A361362.

A361406 Number of bicolored connected cubic graphs on 2n unlabeled vertices with n vertices of each color.

Original entry on oeis.org

1, 0, 1, 5, 63, 1052, 27336, 882321, 34455134, 1558650424, 80016369538, 4589908631503, 290839634055722, 20171917072658395, 1519875854413728667, 123616508830454828043, 10794216583730162449785, 1007179737486515827821590, 100007950522974604304016627, 10529173417583858651114779790, 1171605981584666223513790021758
Offset: 0

Views

Author

Andrew Howroyd, Mar 11 2023

Keywords

Comments

Adjacent vertices may have the same color.

Examples

			a(1) = 1 since the only cubic graph on 4 vertices is the complete graph. The bicolored graphs are indistinguishable whichever 2 vertices are colored in the first color.
		

Crossrefs

Central coefficients of A321304.
Showing 1-6 of 6 results.