a(n) = Sum_{k>=0} binomial(n,5*k+1).

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =7a(7) =14a(8) =36a(9) =93a(10) =220a(11) =474a(12) =948a(13) =1807a(14) =3381a(15) =6385a(16) =12393a(17) =24786a(18) =50559a(19) =103702a(20) =211585a(21) =427351a(22) =854702a(23) =1698458a(24) =3368259a(25) =6690150a(26) =13333932a(27) =26667864a(28) =53457121a(29) =107232053