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

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =7a(7) =22a(8) =57a(9) =127a(10) =254a(11) =474a(12) =859a(13) =1574a(14) =3004a(15) =6008a(16) =12393a(17) =25773a(18) =53143a(19) =107883a(20) =215766a(21) =427351a(22) =843756a(23) =1669801a(24) =3321891a(25) =6643782a(26) =13333932a(27) =26789257a(28) =53774932a(29) =107746282