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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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The terms are congruent to 0 or 1 (mod 3).
LINKS
Samuel S. Wagstaff, Jr. The Cunningham Project
CROSSREFS
Cf. A216519.
Sequence in context: A106077 A216515 A048977 * A342822 A154650 A015913
KEYWORD
nonn
AUTHOR
V. Raman, Sep 08 2012
STATUS
approved

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)