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 1-8 of 8 results.

A140986 Number of n-colorings of the cubical graph.

Original entry on oeis.org

0, 0, 2, 114, 2652, 29660, 198030, 932862, 3440024, 10599192, 28478970, 68716010, 152040372, 313269684, 608134982, 1122341430, 1983307440, 3375066032, 5556852594, 8885943522, 13845350540, 21077015820, 31421193342, 45962742254, 66085098312, 93532729800
Offset: 0

Views

Author

Jonathan Vos Post, Jul 28 2008

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> n^8 -12*n^7 +66*n^6 -214*n^5 +441*n^4 -572*n^3 +423*n^2 -133*n:
    seq(a(n), n=0..30);  # Alois P. Heinz, Mar 01 2009
  • Maxima
    A140986(n):=n^8-12*n^7+66*n^6-214*n^5+441*n^4-572*n^3 +423*n^2-133*n$
    makelist(A140986(n),n,0,30); /* Martin Ettl, Nov 03 2012 */

Formula

a(n) = n^8-12*n^7+66*n^6-214*n^5+441*n^4-572*n^3+423*n^2-133*n.
G.f.: 2*x^2*(1+48*x+849*x^2+4864*x^3+8619*x^4+4848*x^5+931*x^6)/(1-x)^9. - Colin Barker, Apr 15 2012
a(n) = Sum_{k=1..8} k!*binomial(n,k)*A334159(3,k). - Andrew Howroyd, Apr 22 2020

Extensions

More terms from Alois P. Heinz, Mar 01 2009

A334247 Number of acyclic orientations of the edges of an n-dimensional cube.

Original entry on oeis.org

1, 2, 14, 1862, 193270310, 47171704165698393638
Offset: 0

Views

Author

Matthew Scroggs, Apr 20 2020

Keywords

Comments

a(n) is the absolute value of the chromatic polynomial of the n-hypercube graph evaluated at -1.

Examples

			For n=2, there are 14 ways to orient the edges of a square without cycles (see links).
		

Crossrefs

Cf. A334248 is the number of acyclic orientations with rotations and reflections of the same orientation excluded.
Cf. A033815 (cross-polytope), A058809 (wheel), A338152 (demihypercube), A338153 (prism), A338154 (antiprism).

Programs

  • Maple
    with(GraphTheory): with(SpecialGraphs):
    a:= n-> abs(ChromaticPolynomial(HypercubeGraph(n), -1)):
    seq(a(n), n=0..4);  # Alois P. Heinz, Jan 14 2025

Formula

a(n) = Sum_{k=1..2^n} (-1)^(2^n-k) * k! * A334159(n, k). - Andrew Howroyd, Apr 21 2020
a(n) = |Sum_{k=0..2^n} (-1)^k * A334278(n, k)|. - Peter Kagey, Oct 13 2020

Extensions

a(5) from Andrew Howroyd, Apr 23 2020

A334278 Irregular table read by rows: T(n, k) is the coefficient of x^k in the chromatic polynomial of the cubical graph Q_n, 0 <= k <= 2^n.

Original entry on oeis.org

0, 1, 0, -1, 1, 0, -3, 6, -4, 1, 0, -133, 423, -572, 441, -214, 66, -12, 1, 0, -3040575, 14412776, -31680240, 43389646, -41821924, 30276984, -17100952, 7701952, -2794896, 818036, -191600, 35264, -4936, 496, -32, 1
Offset: 0

Views

Author

Peter Kagey, Apr 21 2020

Keywords

Comments

The sums of the absolute values of the entries in each row gives A334247, the number of acyclic orientations of edges of the n-cube.

Examples

			Table begins:
n/k| 0     1    2     3    4     5   6    7  8
---+-------------------------------------------
  0| 0,    1
  1| 0,   -1,   1
  2| 0,   -3,   6,   -4,   1
  3| 0, -133, 423, -572, 441, -214, 66, -12, 1
		

Crossrefs

Cf. A296914 is the reverse of row 3.
Cf. A334279 is analogous for the n-dimensional cross-polytope, the dual of the n-cube.

Programs

  • Maple
    with(GraphTheory): with(SpecialGraphs):
    T:= n-> (p-> seq(coeff(p, x, i), i=0..degree(p)))(
        ChromaticPolynomial(HypercubeGraph(n), x)):
    seq(T(n), n=0..4);  # Alois P. Heinz, Jan 14 2025
  • Mathematica
    T[n_, k_] := Coefficient[ChromaticPolynomial[HypercubeGraph[n], x], x, k]

Formula

T(n,0) = 0.
T(n,k) = Sum_{i=1..2^n}, Stirling1(i,k) * A334159(n,i). - Andrew Howroyd, Apr 25 2020

A334358 Irregular triangle read by rows: row n gives scaled coefficients of the chromatic polynomial corresponding to colorings of the n-hypercube graph up to automorphism, highest powers first, 0 <= k <= 2^n.

Original entry on oeis.org

1, 0, 1, -1, 0, 1, -2, 3, -2, 0, 1, -12, 72, -256, 579, -812, 644, -216, 0, 1, -32, 496, -4936, 35276, -191840, 820328, -2808636, 7759343, -17276144, 30675244, -42494732, 44214736, -32375904, 14772272, -3125472, 0, 1, -80, 3160, -82080, 1575420, -23805776, 294640000
Offset: 0

Views

Author

Andrew Howroyd, Apr 24 2020

Keywords

Comments

The polynomials are scaled by a factor of n!*2^n to ensure integer coefficients. When evaluated at x = k, they give the number of non-isomorphic k-colorings of the n-hypercube graph under the automorphism group of the graph. The size of the automorphism group is n!*2^n. Colors may not be interchanged.

Examples

			Triangle begins:
  0 | 1, 0;
  1 | 1, -1, 0;
  2 | 1, -2, 3, -2, 0;
  3 | 1, -12, 72, -256, 579, -812, 644, -216, 0;
  ...
The corresponding polynomials are:
  x;
  (x^2 - x)/(1!*2^1);
  (x^4 - 2*x^3 + 3*x^2 - 2*x)/(2!*2^2);
  (x^8 - 12*x^7 + 72*x^6 - 256*x^5 + 579*x^4 - 812*x^3 + 644*x^2 - 216*x)/(3!*2^3);
  ...
The polynomial (x^4 - 2*x^3 + 3*x^2 - 2*x)/(2!*2^2) gives A002817 when evaluated at integer values of x.
		

Crossrefs

A296914 List of coefficients of chromatic polynomial of the cubical graph Q_3, highest order terms first.

Original entry on oeis.org

1, -12, 66, -214, 441, -572, 423, -133, 0
Offset: 1

Views

Author

N. J. A. Sloane, Dec 22 2017

Keywords

Crossrefs

Formula

The chromatic polynomial is x^8-12*x^7+66*x^6-214*x^5+441*x^4-572*x^3+423*x^2-133*x.
a(n) = Sum_{k=1..8} Stirling1(k, 9-n)*A334159(3,k). - Andrew Howroyd, Apr 22 2020

A307334 Number of 3-colorings of an n-dimensional hypercube.

Original entry on oeis.org

3, 6, 18, 114, 2970, 1185282, 100301050602
Offset: 0

Views

Author

Aalok Sathe, Jul 24 2019

Keywords

Crossrefs

Cf. A334159.

Formula

a(n) = 3*A334159(n,1) + 6*A334159(n,2) + 6*A334159(n,3). - Andrew Howroyd, Apr 23 2020

Extensions

a(6) from Andrew Howroyd, Apr 23 2020

A295176 Chromatic invariant of the n-hypercube graph.

Original entry on oeis.org

1, 1, 1, 11, 48253, 135327729523895
Offset: 0

Views

Author

Eric W. Weisstein, Nov 16 2017

Keywords

Crossrefs

Formula

a(n) = Sum_{k=2..2^n} (-1)^k*(k-2)!*A334159(n,k) for n > 0. - Andrew Howroyd, Apr 23 2020

Extensions

a(5) from Andrew Howroyd, Apr 23 2020

A334359 Number of stable partitions of the n-hypercube graph.

Original entry on oeis.org

1, 1, 4, 354, 179185930, 258823757396708888836788
Offset: 0

Views

Author

Andrew Howroyd, Apr 25 2020

Keywords

Comments

A stable partition is a partition of the vertices into sets so that no two vertices in a set are adjacent in the graph.
Equivalently, a(n) is the number of vertex colorings of the n-hypercube graph with any number of unlabeled colors. The vertices are not interchangeable.

Examples

			The a(2) = 4 stable partitions of the 2-dimensional hypercube are:
    1---2   1---2   1---2   1---2
    |   |   |   |   |   |   |   |
    2---1   2---3   3---1   3---4
		

Crossrefs

Row sums of A334159.
Showing 1-8 of 8 results.