A128155 a(n) = least k such that the remainder when 15^k is divided by k is n.

2, 13, 6, 11, 10, 533, 218, 119, 12, 145, 214, 57, 106, 17149, 17, 3736136819, 26, 117, 206, 143, 34, 427, 202, 871, 40, 25397, 54, 6877, 52, 115, 194, 6839309, 48, 4857103, 38, 63, 94, 94043, 62, 95, 46, 303, 182, 121214771, 55, 1137417899, 178, 3327, 116

Offset: 1

Author

Alexander Adamchuk, Feb 16 2007

Keywords

• hard
• nonn

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, A128156, A128157, A128158, A128159, A128160, A128149, A128150.

Programs

Mathematica

t = Table[0, {10000} ]; k = 1; While[ k < 3000000000, a = PowerMod[15, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t

Extensions

More terms from Ryan Propper, Feb 28 2007