This sequence needs a meaningful name.

Terms

a(0) =0a(1) =1a(2) =4a(3) =2a(4) =10a(5) =10a(6) =10a(7) =10a(8) =52a(9) =94a(10) =230a(11) =606a(12) =982a(13) =2194a(14) =4388a(15) =8776a(16) =17552a(17) =86840a(18) =277152a(19) =744616a(20) =2597840a(21) =7412896a(22) =20021472a(23) =17423632a(24) =40042944a(25) =74890208a(26) =459732608a(27) =149780416a(28) =1069245632a(29) =1069245632