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A137666
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Largest prime factor of A137664(n) = (p + 1)^p - 1 for p = prime[n].
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2
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2, 7, 311, 337, 266981089, 29914249171, 7563707819165039903, 192696104561, 58769065453824529, 847499019384726257346113954958447091, 18158209813151, 138233050898929517126243814850350442620694127
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) is also largest prime factor of A137665(n) = A137664(n)/Prime(n)^2. p^2 divides A137664(n) = (p + 1)^p - 1, p = Prime[n]. Least prime factors of A137664(n) are listed in A128456(n) = {2,7,311,127,23,157,7563707819165039903,...}. a(n) = A128456(n) = A137665(n) = ((p + 1)^p - 1)/p^2 for n = {1,2,3,7,595,...} corresponding to p = Prime(n) = {2,3,5,17,4357,...} = A127837. a(14) = 7830258625438900077912088739. a(16) = 624260614519341189444454570737302439190642520992875859393.
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CROSSREFS
| Cf. A128452, A128456, A128356, A128357, A137664, A137665, A128466, A127837.
Sequence in context: A012987 A187603 A128456 * A137665 A128466 A048122
Adjacent sequences: A137663 A137664 A137665 * A137667 A137668 A137669
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KEYWORD
| hard,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 04 2008
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