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A056790
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Greatest prime factor of n^n + (n+1)^(n+1).
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6
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2, 5, 31, 283, 23, 743, 331, 1600069, 410353, 60042893, 8969, 7438489991, 116803, 4879633159, 61215157711, 338142271, 34041259347101651, 45072130459, 6564253087266573169, 22022174223585405703, 121937899012999, 69454092876521107983605569601, 5311242856728321929909
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OFFSET
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0,1
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COMMENTS
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Note that n^n + (n+1)^(n+1) = A056788(n+1).
Becomes "hard" (unknown) around n ~ 112, cf. link: As of today, even A217435(113) (number of prime factors) is unknown. - M. F. Hasler, Oct 04 2012
As of today, the first unknown term is a(143). - Daniel Suteu, Mar 11 2019
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LINKS
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FORMULA
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EXAMPLE
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a(4) = 23 because 4^4 + 5^5 = 3381 = 3 * 7^2 * 23.
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MATHEMATICA
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Join[{2}, FactorInteger[Total[#]][[-1, 1]]&/@Partition[Table[n^n, {n, 30}], 2, 1]] (* Harvey P. Dale, Apr 21 2018 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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