A116632 Positive integers n such that 13^n == 7 (mod n).

1, 2, 3, 6, 15, 75, 219, 1335, 3246, 4975, 5475, 7775, 8922, 28614, 67675, 69998, 103135, 313609, 548983, 624193, 6539595, 13193562, 26383395, 111892866, 315953675, 5330142066, 33738816835, 66899423586, 336966134829, 645835313441, 742199683475, 1244107219389, 10187548490537, 760354210440662

Offset

1,2

Comments

No other terms below 10^15. - Max Alekseyev, Oct 30 2018

Some larger terms: 6584692157923407917184426, 3226231185229904054184099310127719809, 30643479515551752620928357020812679775, 5890087594520845596744547263586007316572563275. - Max Alekseyev, Oct 30 2018

Links

Table of n, a(n) for n=1..34.

Mathematica

Join[{1, 2, 3, 6}, Select[Range[1, 9000], Mod[13^#, #] == 7 &]] (* G. C. Greubel, Nov 19 2017 *)
Join[{1, 2, 3, 6}, Select[Range[10000000], PowerMod[13, #, #] == 7 &]] (* Robert Price, Apr 10 2020 *)

Prog

(PARI) isok(n) = Mod(13, n)^n == 7; \\ Michel Marcus, Nov 19 2017

Crossrefs

Cf. A116609, A116611, A116620, A116621, A116622, A116629, A116630, A116631.

Sequence in context: A001529 A363505 A069354 * A214343 A007364 A305857

Adjacent sequences: A116629 A116630 A116631 * A116633 A116634 A116635

Keyword

nonn

Author

Zak Seidov, Feb 19 2006

Extensions

More terms from Ryan Propper, Mar 30 2007

Terms 1,2,3,6 prepended and a(27)-a(34) added by Max Alekseyev, Jun 30 2011, Oct 30 2018

Status

approved