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A317977
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a(n) = A003010(n-2) mod (2^n - 1).
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1
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1, 0, 14, 0, 23, 0, 149, 205, 95, 1736, 779, 0, 4193, 20400, 25439, 0, 221468, 0, 1036394, 840107, 1751891, 6107895, 5639594, 8772568, 66322529, 60611448, 99083624, 458738443, 989927528, 0, 3038229779, 5238898821, 393215, 11960838285, 27264928469, 117093979072, 274827575393, 276971366821
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OFFSET
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2,3
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COMMENTS
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For n > 2, the Mersenne number 2^n - 1 is a prime if and only if a(n) = 0. See comments in A003010.
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LINKS
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FORMULA
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PROG
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(PARI) a(n) = {my(pow = 2^n-1, res = Mod(4, pow)); for(i = 1, n-2, res = res^2 - 2); lift(res)}
(Python)
m = 2**n-1
c = 4 % m
for _ in range(n-2):
c = (c**2-2) % m
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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