a(n) = Sum_{k=0..floor(n/4)} binomial(n-3*k,k) * binomial(2*(n-4*k),n-4*k).

A383582

a(n) = Sum_{k=0..floor(n/4)} binomial(n-3*k,k) * binomial(2*(n-4*k),n-4*k).

Terms

    a(0) =1a(1) =2a(2) =6a(3) =20a(4) =71a(5) =256a(6) =942a(7) =3512a(8) =13221a(9) =50138a(10) =191260a(11) =733088a(12) =2821037a(13) =10892100a(14) =42174848a(15) =163706656a(16) =636816019a(17) =2481902842a(18) =9689155902a(19) =37882580356a(20) =148313102097a(21) =581365577564

External references