OFFSET
1,5
LINKS
Robert Israel, Table of n, a(n) for n = 1..2000
FORMULA
a(n) = Sum_{1<=j<=n/4} binomial(floor(n/3),j)*binomial(n-floor(n/3),3*j). - Robert Israel, Dec 15 2020
MAPLE
f:= proc(n) local t, k;
add(binomial(floor(n/3), k)*binomial(n-floor(n/3), 3*k), k=1..n/4)
end proc:
map(f, [$1..50]); # Robert Israel, Dec 15 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved