a(n) = binomial(10*n,n)*(8*n+1)/(9*n+1).

A215554

a(n) = binomial(10*n,n)*(8*n+1)/(9*n+1).

Terms

    a(0) =1a(1) =9a(2) =170a(3) =3625a(4) =81510a(5) =1888460a(6) =44602348a(7) =1067658735a(8) =25810820750a(9) =628737007195

External references