OFFSET
1,1
COMMENTS
The sequence contains A000979 as a subsequence.
Both m and n must be prime.
LINKS
Robert Israel, Table of n, a(n) for n = 1..39
EXAMPLE
For m=3 and n=5, (2^15-1)/((2^3-1)(2^5-1))=151 is prime, so 151 is a member of the sequence.
MAPLE
N:= 200: # to use all (p, q) with p*q < N
Primes:= select(isprime, [$2..floor(N/2)]):
A:= {}:
for i from 1 to nops(Primes) do
p:= Primes[i];
Qs:= select(q -> q < N/p, [seq(Primes[j], j=1..i-1)]);
A:= A union {seq((2^(p*q)-1)/(2^p-1)/(2^q-1), q=Qs)};
od:
# in Maple 12 and up
select(isprime, A);
# or in earlier Maple versions
sort([select(isprime, , A); # _)[]])[];
# Robert Israel, Sep 02 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Nico Brown, Sep 02 2014
STATUS
approved