a(n) = Sum_{k=0..4} 2^k * binomial(n,k).

Terms

a(0) =1a(1) =3a(2) =9a(3) =27a(4) =81a(5) =211a(6) =473a(7) =939a(8) =1697a(9) =2851a(10) =4521a(11) =6843a(12) =9969a(13) =14067a(14) =19321a(15) =25931a(16) =34113a(17) =44099a(18) =56137a(19) =70491a(20) =87441a(21) =107283a(22) =130329a(23) =156907a(24) =187361a(25) =222051a(26) =261353a(27) =305659a(28) =355377a(29) =410931