a(n) = product of total number of 0's and total number of 1's in binary expansions of 0, ..., n.

Terms

a(0) =0a(1) =1a(2) =4a(3) =8a(4) =20a(5) =35a(6) =54a(7) =72a(8) =117a(9) =165a(10) =221a(11) =280a(12) =352a(13) =425a(14) =504a(15) =576a(16) =726a(17) =875a(18) =1036a(19) =1200a(20) =1386a(21) =1575a(22) =1776a(23) =1976a(24) =2214a(25) =2451a(26) =2700a(27) =2944a(28) =3216a(29) =3479