A128158 a(n) = least k such that the remainder when 18^k is divided by k is n.

17, 14, 5, 7, 13, 106, 11, 158, 927, 314, 6767, 15, 724317787, 62, 21, 20, 407, 19, 319, 38, 39, 302, 150698261, 30, 1055599, 298, 129, 74

Offset: 1

Author

Alexander Adamchuk, Feb 16 2007

Keywords

• hard
• more
• nonn

Comments

10^15 < a(29) <= 3612834616189533302730621726282897865691021. - Max Alekseyev, Apr 14 2012

Links

• Robert G. Wilson v, Table of n, a(n) for n = 1..10000 with -1 for large entries where a(n) has not yet been found

Crossrefs

Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127820, A127821, A128154, A128155, A128156, A128157, A128159, A128160, A128149, A128150.

Programs

Mathematica

t = Table[0, {10000}]; k = 1; While[k < 3000000000, a = PowerMod[18, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t (* Robert G. Wilson v, Jun 23 2009 *)

Extensions

a(13)-a(28) from Robert G. Wilson v, Jun 23 2009