OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..3000
Index entries for linear recurrences with constant coefficients, signature (9,-36,84,-126,126,-84,36,-9,2).
FORMULA
a(n) = Sum_{k=0..floor(n/9)} binomial(n+8,9*k+8).
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + 2*a(n-9) for n > 8.
MATHEMATICA
CoefficientList[Series[1/((1 - x)^9 - x^9), {x, 0, 30}], x] (* Amiram Eldar, May 25 2021 *)
PROG
(PARI) {a(n) = sum(k=0, n\9, binomial(n+8, 9*k+8))}
(PARI) N=66; x='x+O('x^N); Vec(1/((1-x)^9-x^9))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Mar 17 2019
STATUS
approved