id:A136030 - OEIS Search Results

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Smallest prime factor of composite Mersenne numbers.

+0
6

23, 47, 233, 223, 13367, 431, 2351, 6361, 179951, 193707721, 228479, 439, 2687, 167, 11447, 7432339208719, 2550183799, 745988807, 3391 (list; graph; listen)

	OFFSET	`1,1`
	MATHEMATICA	`a = {}; Do[If[PrimeQ[n] && !PrimeQ[2^n - 1], w = 2^n - 1; c = FactorInteger[w]; b = c[[1]][[1]]; AppendTo[a, b]], {n, 2, 130}]; a`
	CROSSREFS	`Cf. A049479, A016047.` `Adjacent sequences: A136027 A136028 A136029 this_sequence A136031 A136032 A136033` `Sequence in context: A065017 A140618 A042052 this_sequence A054693 A052229 A054679`
	KEYWORD	`nonn`
	AUTHOR	`Artur Jasinski (grafix(AT)csl.pl), Dec 11 2007`

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Last modified October 12 14:39 EDT 2008. Contains 144830 sequences.

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