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

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =32a(6) =63a(7) =120a(8) =219a(9) =382a(10) =638a(11) =1024a(12) =1586a(13) =2380a(14) =3473a(15) =4944a(16) =6885a(17) =9402a(18) =12616a(19) =16664a(20) =21700a(21) =27896a(22) =35443a(23) =44552a(24) =55455a(25) =68406a(26) =83682a(27) =101584a(28) =122438a(29) =146596