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A263686
Smallest prime factor of double Mersenne numbers.
3
7, 127, 2147483647, 170141183460469231731687303715884105727, 338193759479, 231733529, 62914441, 295257526626031
OFFSET
1,1
COMMENTS
A double Mersenne number is a Mersenne number of the form 2^(2^p - 1) - 1, where p is a Mersenne exponent (A000043).
LINKS
Double Mersennes Prime Search, History
PROG
(PARI) forprime(p=2, , q=2^p-1; !ispseudoprime(q) && next(); if(ispseudoprime(2^q-1), print1(2^q-1, ", "); next()); forstep(r=2*q+1, +oo, 2*q, !ispseudoprime(r) && next(); if(Mod(2, r)^q-1 == 0, print1(r, ", "); next(2)))) \\ Jeppe Stig Nielsen, Aug 28 2019
CROSSREFS
Cf. A000043, A000668, A077586, A122094. Subsequence of A016047. Subsequence of A309130.
Sequence in context: A077586 A277634 A309130 * A002614 A333561 A187237
KEYWORD
nonn,hard,more
AUTHOR
STATUS
approved