A125556 - OEIS

A125556

Smallest prime p = n*m + 1 that divides m^m - 1 for some m > 1.

3, 11, 61, 13, 31, 241, 43, 257, 271, 251, 1013, 673, 157, 71, 541, 241, 307, 883, 4409, 401, 1471, 463, 5843, 577, 601, 2081, 271, 757, 1973, 241, 2729, 2657, 4951, 1123, 21701, 937, 32191, 14479, 3433, 641, 1723, 2521, 5849, 6689, 1531, 6257, 18143

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OFFSET

1,1

COMMENTS

Corresponding numbers m > 1 such that a(n) divides m^m - 1 are m = (a(n) - 1)/n = {2,5,20,3,6,40,6,32,30,25,92,56,12,5,36,15,18,...}.

LINKS

Joseph L. Wetherell, Table of n, a(n) for n = 1..10000

PROG

(PARI) a(n) = forprime(p=3, , if (!((p-1) % n) && (m = (p-1)/n) && (m > 1) && !((m^m-1) % p), return (p)); ); \\ Michel Marcus, Nov 18 2017

CROSSREFS

Cf. A048861 (n^n - 1).

Sequence in context: A007146 A076475 A354417 * A127516 A228204 A095237