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A137809 a(0) = a(1) = 1. a(n) = a(n-1) + a(n - b(n)), where b(n) is largest prime dividing n. 2
1, 1, 2, 3, 5, 6, 9, 10, 19, 28, 34, 35, 63, 64, 74, 108, 182, 183, 291, 292, 400, 474, 509, 510, 984, 1384, 1448, 2432, 2906, 2907, 4291, 4292, 8583, 9092, 9275, 12181, 21273, 21274, 21566, 23014, 35195, 35196, 47377, 47378, 56470, 91665, 92175, 92176 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Iain Fox, Table of n, a(n) for n = 0..10000 (first 101 terms from James A. Sellers)

FORMULA

a(p) = a(p-1) + 1, for p prime. - Michel Marcus, Aug 11 2018

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][nops(ifactors(n)[2])][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 *)

PROG

(PARI) first(n) = my(res=vector(n)); res[1]=res[2]=1; for(x=3, n, res[x] = res[x-1] + res[x-vecmax(factor(x-1)[, 1])]); res \\ Iain Fox, Aug 11 2018

CROSSREFS

Cf. A006530, A137808.

Sequence in context: A018659 A018365 A018278 * A219035 A273042 A014838

Adjacent sequences:  A137806 A137807 A137808 * A137810 A137811 A137812

KEYWORD

nonn

AUTHOR

Leroy Quet, Feb 11 2008

EXTENSIONS

More terms from Stefan Steinerberger, Feb 14 2008

STATUS

approved

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Last modified August 4 02:09 EDT 2021. Contains 346441 sequences. (Running on oeis4.)