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

Terms

a(0) =0a(1) =4a(2) =31a(3) =141a(4) =506a(5) =1590a(6) =4593a(7) =12523a(8) =32740a(9) =82908a(10) =204755a(11) =495561a(12) =1179582a(13) =2768818a(14) =6422437a(15) =14745495a(16) =33554312a(17) =75759480a(18) =169869159a(19) =378535765a(20) =838860610a(21) =1849687854a(22) =4060086041a(23) =8875147011a(24) =19327352556a(25) =41943039700