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A056187 Least prime factor of n^n + (n+1)^(n+1). 5
2, 5, 31, 283, 3, 67, 11, 11, 5, 173, 3, 1237, 7, 31, 7334881, 227, 3, 773, 149, 47, 11, 5, 3, 101, 13, 73, 151, 349, 3, 4421, 107, 191, 17, 7, 3, 17, 19, 624808693, 2273, 25788481, 3, 5, 59, 1752761753, 23, 2144707, 3, 49547, 5, 275851515609829434269, 19, 919, 3, 13, 7, 107, 29 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Hugo Pfoertner, Table of n, a(n) for n = 0..234, (first 96 terms from Chai Wah Wu).

factordb.com, Status of 235^235+236^236.

Walter Nissen, np(n) = n^n + (n+1)^(n+1) -- 2 prominent questions. (Updated Oct 02 2012)

FORMULA

a(n) = A020639(A056788(n+1)). - M. F. Hasler, Oct 04 2012

EXAMPLE

a(5) = 67 because 5^5 + 6^6 = 3125 + 46656 = 67 * 743.

PROG

(PARI) A056187(n)=factor((n+1)^(n+1)+n^n)[1, 1] \\ M. F. Hasler, Oct 04 2012

CROSSREFS

Cf. A056788, A056790, A192397, A217435.

Sequence in context: A068145 A032112 A058009 * A056790 A192397 A097396

Adjacent sequences:  A056184 A056185 A056186 * A056188 A056189 A056190

KEYWORD

nonn

AUTHOR

Walter Nissen, Aug 20 2000

EXTENSIONS

2 added by Arkadiusz Wesolowski, Jun 30 2011

a(53)-a(56) from Chai Wah Wu, Jul 22 2019

STATUS

approved

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Last modified October 20 11:18 EDT 2019. Contains 328257 sequences. (Running on oeis4.)