A136031 Largest prime factor of composite Mersenne numbers.

89, 178481, 2089, 616318177, 164511353, 2099863, 13264529, 20394401, 3203431780337, 761838257287, 212885833, 9361973132609, 1113491139767, 57912614113275649087721, 13842607235828485645766393, 341117531003194129, 3976656429941438590393

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..183

Formula

a(n) >= A089158(n). - R. J. Mathar, May 01 2008

Mathematica

FactorInteger[2^#-1][[-1, 1]]&/@Select[Prime[Range[40]], !PrimeQ[2^#-1]&] (* Harvey P. Dale, May 05 2012 *)
With[{c=Complement[Prime[Range[PrimePi[200]]], MersennePrimeExponent[ Range[ 15]]]}, Table[ FactorInteger[ 2^p-1][[-1, 1]], {p, c}]] (* Harvey P. Dale, Sep 06 2021 *)

Crossrefs

Cf. A049479, A016047, A003260, A136030.

Sequence in context: A073905 A089158 A145098 * A145097 A287054 A080051

Adjacent sequences: A136028 A136029 A136030 * A136032 A136033 A136034

Keyword

nonn

Author

Artur Jasinski, Dec 11 2007

Extensions

Corrected by Harvey P. Dale, May 05 2012

Status

approved