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 1-10 of 14 results. Next

A115400 Number of n-colorings of the octahedral graph.

Original entry on oeis.org

0, 0, 0, 6, 96, 780, 4080, 15330, 45696, 115416, 257760, 523710, 987360, 1752036, 2957136, 4785690, 7472640, 11313840, 16675776, 24006006, 33844320, 46834620, 63737520, 85443666, 112987776, 147563400, 190538400, 243471150, 308127456
Offset: 0

Views

Author

Jonathan Vos Post, Aug 25 2008

Keywords

Comments

The octahedral graph is the dual of the cubical graph whose chromatic polynomial is evaluated in A140986.

Crossrefs

Cf. A140986.

Programs

  • Magma
    [n*(n-1)*(n-2)*(n^3 - 9*n^2 + 29*n - 32): n in [0..50]]; // Vincenzo Librandi, Feb 12 2012
    
  • Mathematica
    Table[n*(n-1)*(n-2)*(n^3-9*n^2+29*n-32),{n,0,50}] (* Vincenzo Librandi, Feb 12 2012 *)
  • Maxima
    A115400(n):=n*(n-1)*(n-2)*(n^3 - 9*n^2 + 29*n - 32)$
    makelist(A115400(n),n,0,30); /* Martin Ettl, Nov 03 2012 */

Formula

a(n) = n*(n-1)*(n-2)*(n^3 - 9*n^2 + 29*n - 32).
G.f.: 6*x^3*(1 + 9*x + 39*x^2 + 71*x^3)/(1-x)^7. - Colin Barker, Feb 12 2012
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n > 6. - Chai Wah Wu, Jan 19 2024

A334159 Irregular triangle read by rows: T(n,k) is the number of colorings of the n-hypercube graph using exactly k unlabeled colors, k = 1..2^n.

Original entry on oeis.org

1, 0, 1, 0, 1, 2, 1, 0, 1, 18, 92, 146, 80, 16, 1, 0, 1, 494, 54583, 1507094, 12630906, 40096740, 58031885, 43419502, 18212138, 4498756, 670366, 60220, 3156, 88, 1, 0, 1, 197546, 5427041958, 17973998149410, 10961517110194516, 1450479305675145412, 56507865332978414188
Offset: 0

Views

Author

Andrew Howroyd, Apr 21 2020

Keywords

Examples

			Triangle begins:
0 | 1;
1 | 0, 1;
2 | 0, 1, 2, 1;
3 | 0, 1, 18, 92, 146, 80, 16, 1;
4 | 0, 1, 494, 54583, 1507094, 12630906, 40096740, 58031885, 43419502, 18212138, 4498756, 670366, 60220, 3156, 88, 1;
		

Crossrefs

A158348 Number of n-colorings of the Hypercube Graph Q4.

Original entry on oeis.org

0, 0, 2, 2970, 1321860, 187430900, 10199069190, 269591166222, 4221404762120, 44876701584360, 355148098691850, 2230178955481730, 11630998385335692, 52097117078470620, 205557074788375310, 728566149746575350, 2355657801908655120, 7034253747275048912, 19594719516430397970
Offset: 0

Views

Author

Alois P. Heinz, Mar 16 2009

Keywords

Comments

The Hypercube Graph Q4 has 16 vertices and 32 edges.
All terms are even.

Crossrefs

Column k=4 of A342128.

Programs

  • Maple
    a:= n-> n^16 -32*n^15 +496*n^14 -4936*n^13 +35264*n^12 -191600*n^11 +818036*n^10 -2794896*n^9 +7701952*n^8 -17100952*n^7 +30276984*n^6 -41821924*n^5 +43389646*n^4 -31680240*n^3 +14412776*n^2 -3040575*n:
    seq(a(n), n=0..20);

Formula

a(n) = n^16 -32*n^15 + ... (see Maple program).

A268283 Number of distinct directed Hamiltonian cycles of the Platonic graphs (in the order of tetrahedral, cubical, octahedral, dodecahedral, and icosahedral graph).

Original entry on oeis.org

6, 12, 32, 60, 2560
Offset: 1

Views

Author

Melvin Peralta, Jan 29 2016

Keywords

Comments

a(n)/2 is the number of distinct undirected Hamiltonian cycles of the Platonic graph corresponding to a(n).

Crossrefs

Cf. A052762 (tetrahedral graph), A140986 (cubical graph), A115400 (octahedral graph), A218513 (dodecahedral graph), A218514 (icosahedral graph).

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

A218514 Number of n-colorings of the icosahedral graph.

Original entry on oeis.org

0, 0, 0, 0, 240, 80400, 4012560, 76848240, 825447840, 6005512800, 33014872800, 146953113120, 554770648080, 1835249610480, 5448481998960, 14778817981200, 37135461679680, 87386816771520, 194264943433920, 410876964198720, 831638579799600, 1618744884780240
Offset: 0

Views

Author

Eric M. Schmidt, Oct 31 2012

Keywords

References

  • N. Biggs, Algebraic Graph Theory, 2nd ed. Cambridge University Press, 1993. See p. 69.

Crossrefs

Programs

  • Maxima
    A218514(n):=n*(n-1)*(n-2)*(n-3)*(n^8 -24*n^7 +260*n^6 -1670*n^5 +6999*n^4 -19698*n^3 +36408*n^2 -40240*n +20170)$
    makelist(A218514(n), n, 0, 30); /* Martin Ettl, Nov 03 2012 */
  • Sage
    def A218514(n) : return n*(n-1)*(n-2)*(n-3)*(n^8 -24*n^7 +260*n^6 -1670*n^5 +6999*n^4 -19698*n^3 +36408*n^2 -40240*n +20170);
    

Formula

a(n) = n(n-1)(n-2)(n-3)(n^8 -24n^7 +260n^6 -1670n^5 +6999n^4 -19698n^3 +36408n^2 -40240n +20170).
Hence a(n) = n^12 - 30*n^11 + 415*n^10 - 3500*n^9 + 20023*n^8 - 81622*n^7 + 241605*n^6 - 517360*n^5 + 780286*n^4 - 782108*n^3 + 463310*n^2 - 121020*n (cf. A296917) - N. J. A. Sloane, Dec 23 2017
G.f.: -240*x^4*(12547*x^8 +131518*x^7 +481078*x^6 +743494*x^5 +485740*x^4 +128698*x^3 +12442*x^2 +322*x +1)/(x-1)^13. [Colin Barker, Nov 06 2012]

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

A218513 Number of n-colorings of the dodecahedral graph.

Original entry on oeis.org

0, 0, 0, 7200, 168506880, 112603286160, 15108392957760, 775405390866960, 20886647215714560, 353998543659193440, 4231366997071432320, 38508081275604409920, 281586666065022616320, 1720887594454493527920, 9053942417801770507200, 41955877772610102690480
Offset: 0

Views

Author

Eric M. Schmidt, Oct 31 2012

Keywords

References

  • N. Biggs, Algebraic Graph Theory, 2nd ed. Cambridge University Press, 1993. See pp. 69-70.

Crossrefs

Programs

  • Maxima
    A218513(n):=n*(n-1)*(n-2)*(n^17 -27*n^16 +352*n^15 -2950*n^14 +17839*n^13 -82777*n^12 +305866*n^11 -921448*n^10 +2297495*n^9 -4783425*n^8 +8347700*n^7 -12195590*n^6 +14808795*n^5 -14713381*n^4 +11613602*n^3 -6892084*n^2 +2751604*n -555984)$
    makelist(A218513(n), n, 0, 30); /* Martin Ettl, Nov 03 2012 */
  • Sage
    def A218513(n) : return n*(n-1)*(n-2)*(n^17 -27*n^16 +352*n^15 -2950*n^14 +17839*n^13 -82777*n^12 +305866*n^11 -921448*n^10 +2297495*n^9 -4783425*n^8 +8347700*n^7 -12195590*n^6 +14808795*n^5 -14713381*n^4 +11613602*n^3 -6892084*n^2 +2751604*n -555984);
    

Formula

a(n) = n(n-1)(n-2)(n^17 - 27n^16 + 352n^15 - 2950n^14 + 17839n^13 - 82777n^12 + 305866n^11 - 921448n^10 + 2297495n^9 - 4783425n^8 + 8347700n^7 - 12195590n^6 + 14808795n^5 - 14713381n^4 + 11613602n^3 - 6892084n^2 + 2751604n - 555984).
See A296919 for the coefficients of the expanded form of a(n). - N. J. A. Sloane, Dec 23 2017
G.f.: -240*x^3*(2007273*x^17 +678113783*x^16 +62897280675*x^15 +2149103163405*x^14 +32571452423195*x^13 +246267894384141*x^12 +1000326687571911*x^11 +2283861589692665*x^10 +3002531231655465*x^9 +2288662487004975*x^8 +1001857651156729*x^7 +244960098705399*x^6 +31779760521705*x^5 +2006465657455*x^4 +53246253405*x^3 +454442307*x^2 +701482*x +30)/(x-1)^21. - Colin Barker, Nov 06 2012

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

A334356 Number of nonequivalent proper colorings of the vertices of a cube using at most n colors up to rotations and reflections of the cube.

Original entry on oeis.org

0, 1, 15, 154, 1115, 5955, 24836, 85260, 251154, 655005, 1548085, 3374646, 6876805, 13237679, 24271170, 42667640, 72305556, 118640025, 189179979, 294066610, 446766495, 664893691, 971175920, 1394580804, 1971618950, 2747841525, 3779550801, 5135742990, 6900303529
Offset: 1

Views

Author

Andrew Howroyd, Apr 24 2020

Keywords

Comments

Adjacent vertices may not have the same color.
a(n) is the number of nonequivalent n-colorings of the cubical graph up to graph isomorphism.

Crossrefs

Programs

  • PARI
    a(n) = {n*(n - 1)*(n^6 - 11*n^5 + 61*n^4 - 195*n^3 + 384*n^2 - 428*n + 216)/48}

Formula

a(n) = n*(n - 1)*(n^6 - 11*n^5 + 61*n^4 - 195*n^3 + 384*n^2 - 428*n + 216)/48.
a(n) = Sum_{k=1..8} n^k * A334358(3,8-k) / 48.
Showing 1-10 of 14 results. Next