OFFSET
0,3
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).
FORMULA
a(n) = n*(-1+70*n^2-225*n^3+186*n^4)/30.
G.f.: x*(16*x^4+241*x^3+395*x^2+91*x+1) / (x-1)^6.
EXAMPLE
a(3) = 3^4 + 4^4 + 5^4 = 962.
MATHEMATICA
LinearRecurrence[{6, -15, 20, -15, 6, -1}, {0, 1, 97, 962, 4578, 14979}, 30] (* Harvey P. Dale, Jul 30 2017 *)
PROG
(PARI) vector(40, n, n--; sum(k=n, 2*n-1, k^4))
(PARI) concat(0, Vec(x*(16*x^4+241*x^3+395*x^2+91*x+1)/(x-1)^6 + O(x^40)))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Oct 04 2015
STATUS
approved