0,5

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

Eric M. Schmidt, Table of n, a(n) for n = 0..1000

Eric W. Weisstein, Icosahedral Graph

Index entries for linear recurrences with constant coefficients, signature (13,-78,286,-715,1287,-1716,1716,-1287,715,-286,78,-13,1).

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]

CoefficientList[Series[-240x^4(12547x^8+131518x^7+481078x^6+743494x^5+485740x^4+128698x^3+12442x^2+322x+1)/(x-1)^13, {x, 0, 30}], x] (* or *) LinearRecurrence[{13, -78, 286, -715, 1287, -1716, 1716, -1287, 715, -286, 78, -13, 1}, {0, 0, 0, 0, 240, 80400, 4012560, 76848240, 825447840, 6005512800, 33014872800, 146953113120, 554770648080}, 30] (* Harvey P. Dale, Mar 02 2026 *)

(SageMath)

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);

(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 */

Cf. A052762, A140986, A115400, A218513, A296916, A296917..

Sequence in context: A289636 A001943 A052263 * A270054 A213696 A275459

Adjacent sequences: A218511 A218512 A218513 * A218515 A218516 A218517

nonn,easy

Eric M. Schmidt, Oct 31 2012

approved