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 A128149 Least k such that n^k mod k = n-1. 28
 2929, 137243, 4769, 4021227877, 387497, 7342733, 2592842671511, 22963573117, 18659, 120593747, 13757837, 17651, 17149, 16584420001, 613024059983, 407, 39959, 559, 581831, 305197, 235, 459207143, 855782591, 106709, 17678421233, 240055, 11227 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 LINKS Max Alekseyev, Table of n, a(n) for n = 3..41 Robert G. Wilson v et al., Table of n, a(n) for n = 3..1000 with -1 for large entries where a(n) has not yet been found. EXAMPLE a(3) = A078457(2) = 2929. MATHEMATICA t = Table[0, {10000}]; f[n_] := Block[{k = 1}, While[k < 2^23 && PowerMod[n, k, k] + 1 != n, If[ Mod[k, 6] == 1, k += 4, k += 2]]; k]; Do[ If[ t[[n]] == 0, a = f@n; If[a < 2^23, t[[n]] = a; Print[{n, a}]]], {n, 10000}] (* Robert G. Wilson v, Aug 15 2009 *) CROSSREFS Cf. A128150 = least k such that n^k mod k = (n-1)^2 Cf. A128172 = least k such that n^k mod k = n+1. Cf. A128148, A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127820, A127821. Cf. A128154, A128155, A128156, A128157, A128158, A128159, A128160, A128361, A128362, A128363, A128364, A128365, A128366, A128367, A128368, A128369, A129370, A128371, A128372. Sequence in context: A054831 A127490 A237079 * A276671 A251233 A251983 Adjacent sequences:  A128146 A128147 A128148 * A128150 A128151 A128152 KEYWORD hard,nonn AUTHOR Alexander Adamchuk, Feb 16 2007 EXTENSIONS a(6) = A127816(5) = 4021227877 found by Ryan Propper, Feb 21 2007 More terms from Alexander Adamchuk, Feb 28 2007 a(9), a(10) from Hagen von Eitzen, Jul 31 2009 More terms from Robert G. Wilson v, Aug 15 2009 a(30), a(35), a(39), a(45) from Max Alekseyev, May 12 2012 STATUS approved

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Last modified October 17 16:42 EDT 2019. Contains 328120 sequences. (Running on oeis4.)