(1/2) times the sum of the elements of all subsets of [n] whose sum is divisible by two.

Terms

a(0) =0a(1) =0a(2) =1a(3) =6a(4) =20a(5) =60a(6) =168a(7) =448a(8) =1152a(9) =2880a(10) =7040a(11) =16896a(12) =39936a(13) =93184a(14) =215040a(15) =491520a(16) =1114112a(17) =2506752a(18) =5603328a(19) =12451840a(20) =27525120a(21) =60555264a(22) =132644864a(23) =289406976a(24) =629145600a(25) =1363148800a(26) =2944401408a(27) =6341787648a(28) =13623099392a(29) =29192355840