OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1,1,-3,3,-1).
FORMULA
a(n) = floor(3*n^3-9/2*n^2+15/4*n-3/4) for n > 3.
G.f.: -x*(x^9-3*x^8+3*x^7-2*x^6-10*x^5-15*x^4-19*x^3-17*x^2-9*x-1) / ((x-1)^4*(x+1)*(x^2+1)). - Colin Barker, Dec 01 2012
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + a(n-4) - 3*a(n-5) + 3*a(n-6) - a(n-7). - Wesley Ivan Hurt, Apr 20 2021
MATHEMATICA
LinearRecurrence[{3, -3, 1, 1, -3, 3, -1}, {1, 12, 50, 134, 280, 507, 834, 1277, 1855, 2586}, 40] (* Harvey P. Dale, Sep 18 2018 *)
PROG
(PARI) a(n)=round(1/(zeta(4)-sum(k=1, n-1, 1/k^4)))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Benoit Cloitre, Jun 12 2003
STATUS
approved