OFFSET
0,3
LINKS
Index entries for linear recurrences with constant coefficients, signature (7,-20,35,-35,21,-7,1).
FORMULA
a(n) = A369813(7*n).
a(n) = Sum_{k=0..floor(n/2)} binomial(n+5*k,n-2*k).
a(n) = 7*a(n-1) - 20*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7).
G.f.: 1/(1 - x - x^2/(1 - x)^6).
PROG
(PARI) a(n) = sum(k=0, n\2, binomial(n+5*k, n-2*k));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jun 22 2024
STATUS
approved