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

A383573

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

Terms

    a(0) =1a(1) =2a(2) =7a(3) =24a(4) =89a(5) =338a(6) =1311a(7) =5152a(8) =20449a(9) =81778a(10) =328999a(11) =1330008a(12) =5398265a(13) =21984610a(14) =89791103a(15) =367643776a(16) =1508560257a(17) =6201927074a(18) =25540266503a(19) =105336838616a(20) =435035342553

External references