A067935 Let rep(n) be the n-th repunit number, sequence gives values of n such that : rep(n)==rep(2) (mod n).

1, 2, 4, 5, 10, 14, 20, 22, 25, 26, 34, 38, 44, 46, 50, 58, 62, 74, 82, 86, 94, 100, 106, 110, 118, 122, 134, 140, 142, 146, 158, 166, 178, 182, 185, 194, 202, 206, 214, 218, 220, 226, 254, 260, 262, 274, 278, 298, 302, 308, 314, 326, 334, 346, 350, 358, 362

Offset: 1

Author

Benoit Cloitre, Mar 05 2002

Keywords

• nonn

Comments

(10^5-1)/9 = 11+5*2220, hence 5 is in the sequence.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002275, A095250 (rep(n) mod n).

Programs

Maple

filter:= n -> 10&^n -100 mod (9*n) = 0:
select(filter, [$1..400]); # Robert Israel, Jul 02 2019