a(n) = binomial(n*(n+1),n)/(n^2+1).

A135862

a(n) = binomial(n*(n+1),n)/(n^2+1).

Terms

    a(0) =1a(1) =1a(2) =3a(3) =22a(4) =285a(5) =5481a(6) =141778a(7) =4638348a(8) =184138713a(9) =8612835715a(10) =464333035881

External references