

A135434


a(n) is the smallest odd number that makes a(n)*2^N(n)1 prime, where N(n) is the nth Mersenne number that makes 2^N(n)1 prime.


2



3, 3, 7, 3, 9, 7, 51, 15, 69, 19, 25, 103, 1905, 273, 139, 13, 4027, 3619, 2187, 3211, 6621, 1897, 17461, 2511, 90579, 30189, 805, 86539, 30091, 317917, 198681, 755061, 1283911, 26869, 1564347, 4348099, 383731, 6020095
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OFFSET

1,1


COMMENTS

First 22 terms are obtained by Mathematica. Terms from 23 to 38 are obtained by Jean Penna's LLR program.


LINKS



EXAMPLE

First Mersenne number N(1)=2, 2^21=3 is the first Mersenne prime. 3*2^21=11 is prime;
Fifth Mersenne number N(5)=13, 2^131=8191 is the fifth Mersenne prime. 9*2^131=73727 is prime.


CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



EXTENSIONS



STATUS

approved



