OFFSET
0,1
FORMULA
a(n) = A052509(4*n+2,3*n+2) + A052509(4*n+2,n+1) = 2^n + Sum_{m=0..n+1} binomial(3*n+1,m). - Jianing Song, May 30 2022
PROG
(PARI) a(n) = 2^n + sum(m=0, n+1, binomial(3*n+1, m)) \\ Jianing Song, May 30 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved