A137808 a(0) = a(1) = 1. a(n) = a(n-1) + a(n - b(n)), where b(n) is smallest prime dividing n.

1, 1, 2, 3, 5, 6, 11, 12, 23, 34, 57, 58, 115, 116, 231, 346, 577, 578, 1155, 1156, 2311, 3466, 5777, 5778, 11555, 13866, 25421, 36976, 62397, 62398, 124795, 124796, 249591, 374386, 623977, 748772, 1372749, 1372750, 2745499, 4118248, 6863747

Offset

0,3

Links

James A. Sellers, Feb 18 2008, Table of n, a(n) for n = 0..101

Maple

with(numtheory): a:=proc(n) option remember: if n = 0 or n = 1 then RETURN(1) fi: a(n-1) + a(n-ifactors(n)[2][1][1]): end: for i from 0 to 100 do printf(`%d, `, a(i)) od: # James A. Sellers, Feb 18 2008

Mathematica

a = {1, 1}; Do[AppendTo[a, a[[ -1]] + a[[n - FactorInteger[n][[1, 1]] + 1]]], {n, 2, 70}]; a (* Stefan Steinerberger, Feb 14 2008 *)

Crossrefs

Cf. A137809, A020639.

Sequence in context: A117086 A344551 A081026 * A275525 A091909 A171040

Adjacent sequences: A137805 A137806 A137807 * A137809 A137810 A137811

Keyword

nonn

Author

Leroy Quet, Feb 11 2008

Extensions

Corrected and extended by Stefan Steinerberger, Feb 14 2008

Status

approved