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A135977
Mersenne composites (A065341) with exactly 3 prime factors.
9
536870911, 8796093022207, 140737488355327, 9007199254740991, 2361183241434822606847, 9444732965739290427391, 604462909807314587353087
OFFSET
1,1
LINKS
FORMULA
a(n) = 2^A344515(n) - 1. - Amiram Eldar, May 23 2021
MATHEMATICA
k = {}; Do[If[ ! PrimeQ[2^Prime[n] - 1], c = FactorInteger[2^Prime[n] - 1]; d = Length[c]; If[d == 3, AppendTo[k, 2^Prime[n] - 1]]], {n, 1, 40}]; k
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Dec 09 2007
STATUS
approved