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

Terms

a(0) =1a(1) =50a(2) =1375a(3) =27500a(4) =446875a(5) =6256250a(6) =78203125a(7) =893750000a(8) =9496093750a(9) =94960937500a(10) =902128906250