a(n) = binomial(11*n,n)*(9*n+1)/(10*n+1).

A215555

a(n) = binomial(11*n,n)*(9*n+1)/(10*n+1).

Terms

    a(0) =1a(1) =10a(2) =209a(3) =4928a(4) =122507a(5) =3137706a(6) =81921840a(7) =2167714560a(8) =57928578191

External references