a(n) is the number of subsets of {1..n} that contain exactly 4 odd numbers.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =8a(7) =16a(8) =80a(9) =160a(10) =480a(11) =960a(12) =2240a(13) =4480a(14) =8960a(15) =17920a(16) =32256a(17) =64512a(18) =107520a(19) =215040a(20) =337920a(21) =675840a(22) =1013760a(23) =2027520a(24) =2928640a(25) =5857280a(26) =8200192a(27) =16400384a(28) =22364160a(29) =44728320