A076845 - OEIS

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A076845

Least k>0 such that n^k + n - 1 is prime.

1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 16, 1, 1, 4, 3, 1, 2, 1, 1, 4, 1, 3, 2, 1, 2, 10, 1, 1, 108, 3, 1, 2, 1, 1, 2, 2, 1, 2, 1, 3, 2, 1, 2, 20, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 4, 2, 2, 7, 8, 3, 1, 2, 1, 24, 2, 1, 1, 12, 4, 3, 8, 1, 1, 4, 3, 1, 194, 3, 1, 2, 1, 2, 2, 1, 8, 2, 1, 1, 4, 2, 2, 54, 1, 1, 4, 1, 1 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`2,4`
	LINKS	`Table of n, a(n) for n=2..100.`
	MATHEMATICA	`lk[n_]:=Module[{k=1}, While[!PrimeQ[n^k+n-1], k++]; k]; Array[lk, 100, 2] (* Harvey P. Dale, Jun 29 2017 *)`
	PROG	`(PARI) a(n) = {my(k=1); while(!isprime(n^k+n-1), k++); k; } \\ Michel Marcus, Nov 29 2013` `(Haskell)` `a076845 n = head [k \| k <- [1..], a010051'' (n ^ k + n - 1) == 1]` `-- Reinhard Zumkeller, Jul 17 2014`
	CROSSREFS	`Cf. A078178, A076846.` `Cf. A010051.` `Sequence in context: A111178 A279187 A254434 * A161906 A319135 A338884` `Adjacent sequences: A076842 A076843 A076844 * A076846 A076847 A076848`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Cloitre, Nov 20 2002`
	STATUS	`approved`

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Last modified December 28 19:31 EST 2022. Contains 359109 sequences. (Running on oeis4.)