a(n) = Sum_{k=0..n} binomial(3*n,5*k).

Terms

a(0) =1a(1) =1a(2) =7a(3) =127a(4) =859a(5) =6008a(6) =53143a(7) =427351a(8) =3321891a(9) =26789257a(10) =215492564a(11) =1717012749a(12) =13733091643a(13) =109996928003a(14) =879683351911