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 A128160 a(n) = least k such that the remainder when 20^k is divided by k is n. 26
 19, 3, 17, 6, 15, 7, 13, 9, 11, 18, 7989, 92, 973, 33, 611, 24, 2661, 382, 559, 21, 96641237093, 42, 1887, 94, 155, 27, 60403, 36, 7971, 74, 1172954777, 46, 2470227509, 122, 45, 116, 1837, 362, 779, 60, 469, 358, 1275143, 51, 55, 118, 723, 49 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS MATHEMATICA t = Table[0, {10000} ]; k = 1; While[ k < 4000000000, a = PowerMod[20, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t (* Robert G. Wilson v, Aug 04 2009 *) CROSSREFS Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127820, A127821, A128154, A128155, A128156, A128157, A128158, A128159. Cf. A128149, A128150. Sequence in context: A040352 A349406 A040353 * A317319 A002206 A040349 Adjacent sequences:  A128157 A128158 A128159 * A128161 A128162 A128163 KEYWORD hard,nonn AUTHOR Alexander Adamchuk, Feb 16 2007 EXTENSIONS More terms copied from a-file by Hagen von Eitzen, Oct 22 2009 STATUS approved

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Last modified December 7 13:08 EST 2021. Contains 349581 sequences. (Running on oeis4.)