a(n) = 5*binomial(9*n+5,n)/(9*n+5).

A234508

a(n) = 5*binomial(9*n+5,n)/(9*n+5).

Terms

    a(0) =1a(1) =5a(2) =55a(3) =775a(4) =12350a(5) =211876a(6) =3818430a(7) =71282640a(8) =1366368375a(9) =26735839650a(10) =531838637759

External references