A155047 - OEIS

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A155047

a(1) = 1, a(2) = 2, then a(n) = largest prime factor of the partial sum up to a(n-1).

1, 2, 3, 3, 3, 3, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 11, 11, 11, 11, 11, 11, 13, 13, 13, 13, 13, 13, 17, 17, 17, 17, 17, 17, 19, 19, 19, 19, 19, 19, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 29, 29, 29, 29, 29, 29, 29, 29, 31, 31, 31, 31, 31, 31, 31, 31, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 41

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MAPLE

A006530 := proc(n) max(op(numtheory[factorset](n))) ; end:

A155047 := proc(n) option remember; if n <=2 then n; else A006530( add(procname(i), i=1..n-1)) ; fi; end:

seq(A155047(n), n=1..120) ; # R. J. Mathar, Oct 23 2009

MATHEMATICA

nxt[{t_, a_}]:=Module[{lpf=FactorInteger[t][[-1, 1]]}, {t+lpf, lpf}]; Join[ {1}, NestList[ nxt, {3, 2}, 80][[All, 2]]] (* Harvey P. Dale, Aug 06 2018 *)

CROSSREFS

Sequence in context: A056206 A257245 A329245 * A369451 A029088 A253591

Adjacent sequences: A155044 A155045 A155046 * A155048 A155049 A155050

KEYWORD

easy,nonn

AUTHOR

Giovanni Teofilatto, Jan 19 2009

EXTENSIONS

Extended by R. J. Mathar, Oct 23 2009

STATUS

approved