A119715 a(n) = least k such that the remainder when 7^k is divided by k is n.

2, 5, 46, 339, 22, 387497, 11, 535, 10, 111, 38, 8399, 15, 497, 34, 327, 365, 515, 30, 7219931, 28, 321, 26, 223793, 44, 10718597, 242, 35, 2330, 209, 39, 305, 136, 309, 4382, 10596486211, 45, 24751, 7327, 121, 236, 78821, 55, 4117, 76, 1751, 30514339, 83795, 50, 1333

Offset: 1

Author

Ryan Propper, Jun 12 2006

Keywords

• nonn

Links

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

Crossrefs

Cf. A036236, A078457, A119678, A119679, A127816, A119714, A127817, A127818, A127819, A127820, A127821.

Programs

Mathematica

t = Table[0, {10000}]; k = 1; lst = {}; While[k < 4100000000, a = PowerMod[7, k, k]; If[ a<10001 && t[[a]]==0, t[[a]]=k; Print[{a,k}]]; k++ ]; t (* changed (to reflect the new limits) by Robert G. Wilson v, Jul 17 2009 *)
lk[n_]:=Module[{k=1},While[PowerMod[7,k,k]!=n,k++];k]; Array[lk,50] (* The program will take a long time to run. *) (* Harvey P. Dale, Jan 29 2023 *)

Extensions

a(36) = 10596486211 and later terms from Ryan Propper, Feb 02 2007