a(n) = 2^n-n^4.

Terms

a(0) =1a(1) =1a(2) =-12a(3) =-73a(4) =-240a(5) =-593a(6) =-1232a(7) =-2273a(8) =-3840a(9) =-6049a(10) =-8976a(11) =-12593a(12) =-16640a(13) =-20369a(14) =-22032a(15) =-17857a(16) =0a(17) =47551a(18) =157168a(19) =393967a(20) =888576a(21) =1902671a(22) =3960048a(23) =8108767a(24) =16445440a(25) =33163807a(26) =66651888a(27) =133686287a(28) =267820800a(29) =536163631