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Search: id:A136031
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| A136031 |
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Largest prime factor of composite Mersenne numbers. |
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+0
4
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| 89, 178481, 1103, 616318177, 164511353, 9719, 4513, 69431, 3203431780337, 761838257287, 48544121, 2298041, 202029703, 57912614113275649087721, 13842607235828485645766393, 341117531003194129, 3976656429941438590393
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n)>=A089158(n). R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 01 2008
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MATHEMATICA
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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
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CROSSREFS
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Cf. A049479, A016047, A003260, A136030.
Sequence in context: A128872 A073905 A089158 this_sequence A145098 A145097 A080051
Adjacent sequences: A136028 A136029 A136030 this_sequence A136032 A136033 A136034
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Dec 11 2007
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