a(n) = Sum_{k=0..floor(n/3)} binomial(n+k-1,k) * binomial(2*n-k-1,n-3*k).

A378463

a(n) = Sum_{k=0..floor(n/3)} binomial(n+k-1,k) * binomial(2*n-k-1,n-3*k).

Terms

    a(0) =1a(1) =1a(2) =3a(3) =13a(4) =59a(5) =266a(6) =1203a(7) =5489a(8) =25259a(9) =117022a(10) =545038a(11) =2549592a(12) =11970035a(13) =56372460a(14) =266194295a(15) =1259910113a(16) =5975382699a(17) =28390616727a(18) =135108035502a(19) =643891031826

External references