Sum of binary numbers with n 1's and one (non-leading) 0.

Terms

a(0) =0a(1) =2a(2) =11a(3) =38a(4) =109a(5) =284a(6) =699a(7) =1658a(8) =3833a(9) =8696a(10) =19447a(11) =42998a(12) =94197a(13) =204788a(14) =442355a(15) =950258a(16) =2031601a(17) =4325360a(18) =9175023a(19) =19398638a(20) =40894445a(21) =85983212a(22) =180355051a(23) =377487338a(24) =788529129a(25) =1644167144a(26) =3422552039a(27) =7113539558a(28) =14763950053