A236485 Primes p such that gpf(lpf(m)-1) = gpf(gpf(m)-1), where m = 2^p-1 is Mersenne composite.

11, 29, 53

Offset: 1

Author

Thomas Ordowski, Jan 27 2014

Keywords

• nonn
• more
• bref

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

Links

• GIMPS, Exponent Status

Crossrefs

Cf. A003260, A016047, A236128.

Programs

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