A217530 a(n) = n^4/2-5*n^3/2+21*n-30.

0, 6, 22, 75, 204, 460, 906, 1617, 2680, 4194, 6270, 9031, 12612, 17160, 22834, 29805, 38256, 48382, 60390, 74499, 90940, 109956, 131802, 156745, 185064, 217050, 253006, 293247, 338100, 387904, 443010, 503781, 570592, 643830, 723894, 811195, 906156, 1009212, 1120810

Offset

2,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 2..1000

W. Griffiths, R. Smith, and D. Warren, Almost avoiding pairs of permutations, PU. M. A. Vol. 22 (2011), 129-139.

Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

Formula

G.f.: x^3*(11*x^3-25*x^2+8*x-6)/(x-1)^5. - Colin Barker, Oct 17 2012

a(n) = 5*a(n-1)-10*a(n-2)+10*a(n-3)-5*a(n-4)+a(n-5). - Wesley Ivan Hurt, Nov 10 2014

E.g.f.: 30 + 11*x + exp(x)*(x^4 + x^3 - 8*x^2 + 38*x - 60)/2. - Stefano Spezia, Aug 29 2025

Maple

A217530:=n->n^4/2-5*n^3/2+21*n-30: seq(A217530(n), n=2..50); # Wesley Ivan Hurt, Nov 10 2014

Mathematica

Table[n^4/2 - 5 n^3/2 + 21 n - 30, {n, 2, 40}] (* Vincenzo Librandi, Mar 11 2013 *)
LinearRecurrence[{5, -10, 10, -5, 1}, {0, 6, 22, 75, 204}, 40] (* Harvey P. Dale, Dec 12 2018 *)

Prog

(Maxima) makelist(n^4/2-5*n^3/2+21*n-30, n, 2, 40); /* Martin Ettl, Oct 15 2012 */
(Magma) [n^4/2-5*n^3/2+21*n-30: n in [2..40]]; // Vincenzo Librandi, Mar 11 2013

Crossrefs

Sequence in context: A276779 A159555 A032195 * A111566 A372239 A387376

Adjacent sequences: A217527 A217528 A217529 * A217531 A217532 A217533

Keyword

nonn,easy

Author

N. J. A. Sloane, Oct 13 2012

Status

approved