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 A050259 Numbers n such that 2^n == 3 (mod n). 27
 1, 4700063497, 3468371109448915, 8365386194032363, 10991007971508067 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS No other terms below 10^18. - Max Alekseyev, Oct 17 2017 Terms were computed: a(2) by the Lehmers, a(3) by Max Alekseyev, a(4) and a(5) by Joe K. Crump, a(?) = 63130707451134435989380140059866138830623361447484274774099906755 by P.-L. Montgomery. REFERENCES R. Daniel Mauldin and S. M. Ulam, Mathematical problems and games. Adv. in Appl. Math. 8 (1987), pp. 281-344. LINKS Joe K. Crump, 2^n mod n R. K. Guy, The Strong Law of Small Numbers, Amer. Math. Monthly 95 (1988), pp. 697-712. See example 13. R. K. Guy, The strong law of small numbers. Amer. Math. Monthly 95 (1988), no. 8, 697-712. [Annotated scanned copy] Eric Weisstein's World of Mathematics, 2 OEIS Wiki, 2^n mod n MATHEMATICA m = 2; Join[Select[Range[m], Divisible[2^# - m, #] &], Select[Range[m + 1, 10^6], PowerMod[2, #, #] == m &]] (* Robert Price, Oct 08 2018 *) PROG (PARI) is(n)=Mod(2, n)^n==3 \\ Charles R Greathouse IV, Jun 11 2015 CROSSREFS Cf. A001567, A036236, A015940, A015910. Sequence in context: A199631 A124977 A128172 * A249972 A233494 A175568 Adjacent sequences:  A050256 A050257 A050258 * A050260 A050261 A050262 KEYWORD nonn,more,hard AUTHOR STATUS approved

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Last modified May 8 18:28 EDT 2021. Contains 343666 sequences. (Running on oeis4.)