A177494 Least m > 1 such that m^m - 1 is divisible by a prime of the form n*m + 1 = A125556(n).

2, 5, 20, 3, 6, 40, 6, 32, 30, 25, 92, 56, 12, 5, 36, 15, 18, 49, 232, 20, 70, 21, 254, 24, 24, 80, 10, 27, 68, 8, 88, 83, 150, 33, 620, 26, 870, 381, 88, 16, 42, 60, 136, 152, 34, 136, 386, 81, 324, 192, 246, 78, 786, 37, 18, 23, 86, 57, 60, 67, 558, 249, 484, 33, 636

Offset: 1

Author

Alexander Adamchuk, May 10 2010

Keywords

• nonn

Links

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

Crossrefs

Cf. A125556 (smallest prime p = n*m + 1 that divides m^m - 1 for some m > 1).

Programs

PARI

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

Formula

a(n) = (A125556(n) - 1)/n.