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A136031
Largest prime factor of composite Mersenne numbers.
7
89, 178481, 2089, 616318177, 164511353, 2099863, 13264529, 20394401, 3203431780337, 761838257287, 212885833, 9361973132609, 1113491139767, 57912614113275649087721, 13842607235828485645766393, 341117531003194129, 3976656429941438590393
OFFSET
1,1
LINKS
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
KEYWORD
nonn
AUTHOR
Artur Jasinski, Dec 11 2007
EXTENSIONS
Corrected by Harvey P. Dale, May 05 2012
STATUS
approved