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A327660
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Least number k > n - 2 such that k*n^k + 1 is prime.
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1
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1, 1, 2, 3, 1242, 91, 34, 17, 12382, 9, 10, 247
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OFFSET
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1,3
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COMMENTS
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Different version of A240234. Some authors, like Caldwell (link), require that k + 2 > n before they use the term generalized Cullen for a prime of form k*n^k + 1.
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LINKS
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EXAMPLE
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To find a(9), consider numbers k*9^k + 1 where k > 7. The first time it is prime, is for k = 12382, so a(9) = 12382.
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PROG
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(PARI) for(b=1, +oo, for(k=b-1, +oo, if(ispseudoprime(k*b^k+1), print1(k, ", "); next(2))))
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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STATUS
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approved
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