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A007571 a(n) = largest prime factor of n^n + 1.
(Formerly M1343)
8
2, 5, 7, 257, 521, 97, 911, 673, 530713, 27961, 58367, 2227777, 79301, 176597, 142111, 67280421310721, 45957792327018709121, 33388093, 870542161121, 4406613081041681, 22864311556633, 73194743542229, 1522029233, 27250359649 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Hugo Pfoertner, Table of n, a(n) for n = 1..123

factordb, Status of 120^120+1 ... 139^139+1.

FORMULA

a(n) = A006530(A014566(n)). - Michel Marcus, Aug 24 2019

MATHEMATICA

Table[ FactorInteger[ n^n + 1, FactorComplete -> True ] [ [ -1, 1 ] ], {n, 1, 25} ]

PROG

(PARI) for(k=1, 24, my(x=factor(k^k+1), f=x[#x[, 1], 1]); print1(f, ", ")) \\ Hugo Pfoertner, Aug 23 2019

(MAGMA) [Max(PrimeDivisors(n^n+1)):n in [1..24]]; // Marius A. Burtea, Aug 24 2019

CROSSREFS

Cf. A006530, A006486, A014566, A056790.

Sequence in context: A042673 A214705 A252283 * A062621 A306748 A241292

Adjacent sequences:  A007568 A007569 A007570 * A007572 A007573 A007574

KEYWORD

nonn,hard

AUTHOR

N. J. A. Sloane, Robert G. Wilson v

STATUS

approved

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Last modified October 23 22:36 EDT 2019. Contains 328377 sequences. (Running on oeis4.)