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A128126

Numbers k such that 2^k == 18 (mod k).

1, 2, 14, 35, 77, 98, 686, 1715, 5957, 18995, 26075, 43921, 49901, 52334, 86555, 102475, 221995, 250355, 1228283, 1493597, 4260059, 6469715, 10538675, 15374219, 19617187, 22731275, 53391779, 60432239, 68597795, 85672139, 175791077

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Joe Crump (joecr(AT)carolina.rr.com) Table of n, a(n) for n = 1..50

Joe K. Crump, 2^n mod n

MATHEMATICA

m = 18; Join[Select[Range[m], Divisible[2^# - m, #] &],

Select[Range[m + 1, 10^6], PowerMod[2, #, #] == m &]] (* Robert Price, Oct 08 2018 *)

Join[{1, 2, 14}, Select[Range[86*10^6], PowerMod[2, #, #]==18&]] (* Harvey P. Dale, Feb 23 2025 *)

PROG

(PARI) isok(n) = Mod(2, n)^n == 18; \\ Michel Marcus, Oct 09 2018

(Magma) [1, 2, 14] cat [n: n in [1..10^8] | Modexp(2, n, n) eq 18]; // Vincenzo Librandi, Apr 05 2019

CROSSREFS

Cf. A015910, A036236, A050259 (numbers k such that 2^k == 3 (mod k)), A033981, A051447, A033982, A051446, A033983, A128121, A128122, A128123, A128124, A128125.

Sequence in context: A230894 A291152 A145910 * A367646 A367578 A134647

Adjacent sequences: A128123 A128124 A128125 * A128127 A128128 A128129

KEYWORD

nonn

AUTHOR

Alexander Adamchuk, Feb 15 2007

EXTENSIONS

More terms from Joe Crump (joecr(AT)carolina.rr.com), Mar 04 2007

1, 2 and 14 added by N. J. A. Sloane, Apr 23 2007

STATUS

approved

URL: https://oeis.org/A128126

⇱ A128126 - OEIS