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Search: id:A091824
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| A091824 |
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Number p such that ((p-1)!*2^(p-1) + 1)/p is a prime. |
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+0
2
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OFFSET
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0,2
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COMMENT
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1 is not prime but (1-1)!*2^(1-1) + 1 = 2 is a prime than by convention a(1)=1 if p is a prime and gcd(q,p)=1 then p divide (p-1)!*q^(p-1) + 1
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EXAMPLE
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((1-1)!*2^(1-1) + 1)/1 = 2 is a prime than a(1)=1
((3-1)!*2^(3-1) + 1)/3 = 3 is a prime than a(2)=3
((37-1)!*2^(37-1) +1)/37 = 690896939629347629014331483828706966091078572972973 is a prime than a(3)=37
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PROGRAM
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(PARI) for (i=3, 1100, if(isprime(((i-1)!*2^(i-1)+1)/i), print(i)));
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CROSSREFS
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Cf. A091825.
Sequence in context: A106103 A106996 A047691 this_sequence A139842 A056408 A056398
Adjacent sequences: A091821 A091822 A091823 this_sequence A091825 A091826 A091827
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KEYWORD
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hard,more,bref,nonn
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AUTHOR
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Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Mar 09 2004
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