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A136030 Smallest prime factor of composite Mersenne numbers. 6
23, 47, 233, 223, 13367, 431, 2351, 6361, 179951, 193707721, 228479, 439, 2687, 167, 11447, 7432339208719, 2550183799, 745988807, 3391, 263, 32032215596496435569, 5625767248687, 86656268566282183151, 18121, 852133201, 150287, 2349023, 730753, 359, 43441, 383 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..150

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

PROG

(PARI) lista() = {vi = readvec("c:/gp/bfiles/b054723.txt"); vm = vector(#vi, i, 2^vi[i]-1); for (i=1, #vm, print1(factor(vm[i])[1, 1], ", "); ); } \\ Michel Marcus, May 14 2014

CROSSREFS

Cf. A049479, A016047.

Sequence in context: A065017 A140618 A042052 * A054693 A180945 A052229

Adjacent sequences:  A136027 A136028 A136029 * A136031 A136032 A136033

KEYWORD

nonn

AUTHOR

Artur Jasinski, Dec 11 2007

EXTENSIONS

More terms from Michel Marcus, May 14 2014

STATUS

approved

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Last modified April 16 18:53 EDT 2021. Contains 343050 sequences. (Running on oeis4.)