The number of odd entries in all the 2-compositions of n.

Terms

a(0) =0a(1) =2a(2) =10a(3) =48a(4) =208a(5) =864a(6) =3472a(7) =13640a(8) =52664a(9) =200616a(10) =755992a(11) =2823688a(12) =10468856a(13) =38570504a(14) =141341944a(15) =515532424a(16) =1872673144a(17) =6777925768a(18) =24453094264a(19) =87966879368a(20) =315629269368