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A216518
Prime numbers n such that 2^n-1 is prime and can be written in the form a^2+7*b^2.
1
3, 7, 13, 19, 31, 61, 127, 607, 1279, 2203, 2281, 3217, 4423, 23209, 44497, 110503, 132049, 216091, 1257787, 13466917, 20996011, 24036583, 30402457, 42643801
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OFFSET
1,1
COMMENTS
The terms are congruent to 0 or 1 (mod 3).
LINKS
Table of n, a(n) for n=1..24.
Samuel S. Wagstaff, Jr.
The Cunningham Project
CROSSREFS
Cf.
A216519
.
Sequence in context:
A106077
A216515
A048977
*
A342822
A154650
A015913
Adjacent sequences:
A216515
A216516
A216517
*
A216519
A216520
A216521
KEYWORD
nonn
AUTHOR
V. Raman
, Sep 08 2012
STATUS
approved
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Last modified August 16 10:17 EDT 2024. Contains 375174 sequences. (Running on oeis4.)