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A152952
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Von Staudt primes which are not safe primes (A005385).
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0
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239, 443, 647, 659, 827, 1223, 1259, 1499, 1787, 1847, 2087, 2243, 2339, 2687, 2699, 3299, 3659, 3767, 4943, 5903, 6263, 6287, 6299, 6563, 6863, 6959, 7043, 7487, 7583, 7883, 7907, 7919, 8087, 8219, 8243, 8387, 8627, 8663
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..38.
P. Luschny, Von Staudt prime number, definition and computation.
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EXAMPLE
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239 is a von Staudt prime because the denominator(B(239-1)/(239-1))=239*12, where B(n) is the Bernoulli number, but (239-1)/2=119=7*17 is not a prime.
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MAPLE
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a := proc(n) local k, L; L:= []; for k from 11 by 12 to n do map(i->i+1, divisors(k-1)); select(isprime, %) minus {2, 3}; if % = {k} then L := [op(L), k] fi; od; select(isprime, map(i->i+i+1, select(isprime, [$1..iquo(n, 2)]))): sort(convert(convert(L, set) minus convert(%, set), list)): end:
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CROSSREFS
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Cf. A092307, A005385 and A152951.
Sequence in context: A140032 A056086 A046012 * A142356 A142557 A164290
Adjacent sequences: A152949 A152950 A152951 * A152953 A152954 A152955
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KEYWORD
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nonn
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AUTHOR
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Peter Luschny, Dec 25 2008
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STATUS
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approved
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