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A119653
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Denominator of BernoulliB[2p] divided by 6, where p=Prime[n].
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0
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5, 7, 11, 1, 23, 1, 1, 1, 47, 59, 1, 1, 83, 1, 1, 107, 1, 1, 1, 1, 1, 1, 167, 179, 1, 1, 1, 1, 1, 227, 1, 263, 1, 1, 1, 1, 1, 1, 1, 347, 359, 1, 383, 1, 1, 1, 1, 1, 1, 1, 467, 479, 1, 503, 1, 1, 1, 1, 1, 563, 1, 587, 1, 1, 1, 1, 1, 1, 1, 1, 1, 719, 1, 1, 1, 1, 1, 1, 1, 1, 839, 1, 863, 1, 1
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OFFSET
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1,1
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COMMENTS
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a(n) is equal to 1 or a safe prime p: (p-1)/2 is also prime, A005385[n] = 5,7,11,23,47,59,83,107,167,179,227,263,347,359,383,467,479,503,563,587,719,839,863,887,983,1019... The indices of primes in a(n) are n=1,2,3,5,9,10,13,16,23,24..=A072192[n] Indices of Sophie Germain primes: p and 2p+1 are primes.
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LINKS
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FORMULA
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a(n) = Denominator[BernoulliB[2Prime[n]]]/6.
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MATHEMATICA
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Table[Denominator[BernoulliB[2Prime[n]]]/6, {n, 1, 100}]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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