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

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

Offset

0,4

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.

Links

Table of n, a(n) for n=0..9.

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 *)

Crossrefs

Cf. A000659.

Sequence in context: A066535 A134455 A191700 * A261489 A286936 A323948

Adjacent sequences: A000640 A000641 A000642 * A000644 A000645 A000646

Keyword

nonn

Author

N. J. A. Sloane

Extensions

1 more term from Vladeta Jovovic, Mar 19 2000

Status

approved