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A246758
Prime numbers of the form (2^(m*n)-1)/((2^m-1)*(2^n-1)).
1
3, 11, 43, 151, 683, 2731, 43691, 174763, 599479, 2796203, 715827883, 2932031007403, 10052678938039, 145295143558111, 581283643249112959, 658812288653553079, 768614336404564651, 9520972806333758431, 201487636602438195784363
OFFSET
1,1
COMMENTS
The sequence contains A000979 as a subsequence.
Both m and n must be prime.
LINKS
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
Primes in A140803.
Sequence in context: A106876 A034477 A140803 * A342632 A084643 A364865
KEYWORD
nonn
AUTHOR
Nico Brown, Sep 02 2014
STATUS
approved