A116631 Positive integers n such that 13^n == 6 (mod n).

1, 7, 8743, 50239, 312389, 8789977, 87453889, 96301009, 3963715129, 5062673539, 6854133309107, 16987071590111, 72278468169733, 411419589731633, 590475819370933

Offset: 1

Author

Zak Seidov, Feb 19 2006

Keywords

• nonn

Comments

No other terms below 10^15. A large term: 2455610470454186971078168169. - Max Alekseyev, Dec 19 2017

Crossrefs

Solutions to 13^n == k (mod n): A001022 (k=0), A015963 (k=-1), A116621 (k=1), A116622 (k=2), A116629 (k=3), A116630 (k=4), A116611 (k=5), this sequence (k=6), A116632 (k=7), A295532 (k=8), A116636 (k=9), A116620(k=10), A116638 (k=11), A116639 (k=15).

Cf. A116609, A128122, A277628, A277350.

Programs

Mathematica

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

PARI

isok(n) = Mod(13, n)^n == 6; \\ Michel Marcus, Nov 19 2017

Extensions

More terms from Ryan Propper, Mar 30 2007

Term 1 is prepended and a(11)-a(15) added by Max Alekseyev, Jun 29 2011, Dec 19 2017