Euler transform of powers of 4.

Terms

a(0) =1a(1) =4a(2) =26a(3) =148a(4) =843a(5) =4632a(6) =25124a(7) =133784a(8) =703553a(9) =3655340a(10) =18800886a(11) =95819580a(12) =484416675a(13) =2431094352a(14) =12120072472a(15) =60058765072a(16) =295959923287