A135916 (n^4 - 10*n^2 + 15*n - 6)/2.

0, 0, 15, 75, 222, 510, 1005, 1785, 2940, 4572, 6795, 9735, 13530, 18330, 24297, 31605, 40440, 51000, 63495, 78147, 95190, 114870, 137445, 163185, 192372, 225300, 262275, 303615, 349650, 400722, 457185, 519405, 587760, 662640, 744447, 833595, 930510

Offset

1,3

Links

Table of n, a(n) for n=1..37.

Ellingsrud, Geir and Stromme, Stein Arild, Bott's formula and enumerative geometry, J. Amer. Math. Soc. 9 (1996), 175-193. [arXiv:alg-geom/9411005]

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

Formula

a(1)=0, a(2)=0, a(3)=15, a(4)=75, a(5)=222, a(n)=5*a(n-1)-10*a(n-2)+ 10*a(n-3)- 5*a(n-4)+a(n-5). - Harvey P. Dale, Aug 12 2013

G.f.: 3*x^3*(-5+x^2) / (x-1)^5 . - R. J. Mathar, Apr 23 2015

Mathematica

Table[(n^4-10n^2+15n-6)/2, {n, 40}] (* or *) LinearRecurrence[ {5, -10, 10, -5, 1}, {0, 0, 15, 75, 222}, 40] (* Harvey P. Dale, Aug 12 2013 *)

Crossrefs

Sequence in context: A317657 A339518 A296193 * A211812 A266395 A260550

Adjacent sequences: A135913 A135914 A135915 * A135917 A135918 A135919

Keyword

nonn,easy

Author

N. J. A. Sloane, Mar 07 2008

Status

approved