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A128452
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Least number k > n such that k^2 divides n^k - 1.
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4
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4, 21, 6, 1555, 8, 889, 10, 111, 12, 253, 14, 2041, 16, 21, 18, 128583032925805678351, 20, 1432001198261, 22, 39, 24, 1081, 26, 55, 28, 171, 30, 279241, 32, 9641, 34, 1191, 36, 55, 38, 950123, 40, 1641, 42, 33661, 44, 32627169461820247, 46, 63, 48, 583223, 50
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OFFSET
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3,1
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COMMENTS
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For prime p, p divides a(p+1). Quotients a(p+1)/p for prime p = A000040(n) are listed in A128456(n) which coincides with A128357(n) for n from 2 to 6.
a(n) divides n^(n-1) - 1.
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LINKS
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FORMULA
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a(2n-1) = 2n.
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CROSSREFS
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Cf. A128456, A128357, A128356, A127103, A127104, A127105, A127106, A127107, A127102, A127101, A127100, A127092, A128393, A128394, A128395, A128396, A128397, A128398, A128399, A128400, A128401, A128402, A128403, A128404.
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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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