a(n) = binomial(n, 2^floor(log_2(n))).

Terms

a(0) =1a(1) =1a(2) =3a(3) =1a(4) =5a(5) =15a(6) =35a(7) =1a(8) =9a(9) =45a(10) =165a(11) =495a(12) =1287a(13) =3003a(14) =6435a(15) =1a(16) =17a(17) =153a(18) =969a(19) =4845a(20) =20349a(21) =74613a(22) =245157a(23) =735471a(24) =2042975a(25) =5311735a(26) =13037895a(27) =30421755a(28) =67863915a(29) =145422675