a(n) = binomial(n+4, 4)*7^n.

Terms

a(0) =1a(1) =35a(2) =735a(3) =12005a(4) =168070a(5) =2117682a(6) =24706290a(7) =271769190a(8) =2853576495a(9) =28852829005a(10) =282757724249