a(n) = 6*binomial(5*n + 6,n)/(5*n + 6).

Terms

a(0) =1a(1) =6a(2) =45a(3) =380a(4) =3450a(5) =32886a(6) =324632a(7) =3290040a(8) =34034715a(9) =357919100a(10) =3815041230a(11) =41124015036a(12) =447534498320