A000643 a(n) = a(n-1) + 2^a(n-2).

0, 0, 1, 2, 4, 8, 24, 280, 16777496, 1942668892225729070919461906823518906642406839052139521251812409738904285205225275672

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Comments

The next term is too large to include.

The next term has 5050530 digits. - Harvey P. Dale, Jan 05 2024

References

• D. E. Knuth, personal communication.

Crossrefs

Cf. A000659.

Programs

Mathematica

Off[General::ovfl];a={1,0};Flatten[Prepend[Table[s=Plus@@a;a=2^(RotateLeft[a]);a[[ -1]]=s,{n,8}],Table[0,{m,Length[a]-1}]]] (* Vladimir Joseph Stephan Orlovsky, Nov 18 2009 *)
nxt[{a_,b_}]:={b,b+2^a}; NestList[nxt,{0,0},9][[;;,1]] (* Harvey P. Dale, Jan 05 2024 *)

Extensions

1 more term from Vladeta Jovovic, Mar 19 2000