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A136031 Largest prime factor of composite Mersenne numbers. 3
89, 178481, 1103, 616318177, 164511353, 9719, 4513, 69431, 3203431780337, 761838257287, 48544121, 2298041, 202029703, 57912614113275649087721, 13842607235828485645766393, 341117531003194129, 3976656429941438590393 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

FORMULA

a(n)>=A089158(n). R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 01 2008

MATHEMATICA

a = {}; Do[If[PrimeQ[n] && !PrimeQ[2^n - 1], w = 2^n - 1; c = FactorInteger[w]; d = Length[c[[1]]]; b = c[[d]][[1]]; AppendTo[a, b]], {n, 2, 130}]; a

CROSSREFS

Cf. A049479, A016047, A003260, A136030.

Sequence in context: A128872 A073905 A089158 * A145098 A145097 A080051

Adjacent sequences:  A136028 A136029 A136030 * A136032 A136033 A136034

KEYWORD

nonn

AUTHOR

Artur Jasinski (grafix(AT)csl.pl), Dec 11 2007

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Last modified February 14 23:04 EST 2012. Contains 205686 sequences.