OFFSET
1,5
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..500
FORMULA
a(n) = Sum_{k>=1} binomial(floor(n/2), k)*binomial(ceiling(n/2), 3*k). - Andrew Howroyd, Apr 11 2021
PROG
(PARI) a(n) = {my(m=n\2); sum(k=1, (n-m)\3, binomial(m, k)*binomial(n-m, 3*k))} \\ Andrew Howroyd, Apr 11 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Terms a(35) and beyond from Andrew Howroyd, Apr 11 2021
STATUS
approved