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A236485
Primes p such that gpf(lpf(m)-1) = gpf(gpf(m)-1), where m = 2^p-1 is Mersenne composite.
0
OFFSET
1,1
COMMENTS
Conjecture: finitely many such p and gpf(lpf(m)-1) = gpf(gpf(m)-1) = p.
No more terms found up to p = 1277, 1277 being the first prime for which the complete factorization of 2^p-1 is not currently known (see GIMPS link). - Michel Marcus, Jan 29 2014
PROG
(PARI) isok(p) = isprime(p) && (mc = (2^p-1)) && (mcpf = (factor(2^p-1))[, 1]) && (length(mcpf) > 1) && (gpf = vecmax(mcpf)) && (lpf = vecmin(mcpf)) && (vecmax(factor(gpf-1)[, 1]) == vecmax(factor(lpf-1)[, 1])); \\ Michel Marcus, Jan 27 2014
CROSSREFS
KEYWORD
nonn,more,bref
AUTHOR
Thomas Ordowski, Jan 27 2014
STATUS
approved