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

A371399

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

Terms

    a(0) =1a(1) =2a(2) =12a(3) =60a(4) =340a(5) =1932a(6) =11256a(7) =66264a(8) =394020a(9) =2359500a(10) =14211912a(11) =86004360a(12) =522502344a(13) =3184844600a(14) =19467675120a(15) =119288938800a(16) =732508344516

External references