a(n) = binomial(2*n, n) * binomial(2*n - 1, n).

A361877

a(n) = binomial(2*n, n) * binomial(2*n - 1, n).

Terms

    a(0) =1a(1) =2a(2) =18a(3) =200a(4) =2450a(5) =31752a(6) =426888a(7) =5889312a(8) =82818450a(9) =1181952200a(10) =17067389768a(11) =248817153312

External references