a(n) = 2^n + n^2.

Terms

a(0) =1a(1) =3a(2) =8a(3) =17a(4) =32a(5) =57a(6) =100a(7) =177a(8) =320a(9) =593a(10) =1124a(11) =2169a(12) =4240a(13) =8361a(14) =16580a(15) =32993a(16) =65792a(17) =131361a(18) =262468a(19) =524649a(20) =1048976a(21) =2097593a(22) =4194788a(23) =8389137a(24) =16777792a(25) =33555057a(26) =67109540a(27) =134218457a(28) =268436240a(29) =536871753