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 A127817 a(n) = least k such that the remainder when 9^k is divided by k is n. 46
 2, 7, 6, 5, 38, 723, 74, 2592842671511, 11, 3827, 14, 717, 34, 59035, 21, 259, 152, 237, 62, 626131, 30, 169, 58, 25, 56, 1921, 39, 361, 65, 49, 63010, 287, 48, 55, 46, 63, 932, 3786791, 69, 69637, 230, 221, 6707, 1057, 57, 4907, 253, 681, 148, 393217991, 70 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Fausto A. C. Cariboni, Table of n, a(n) for n = 1..10000 with -1 for large entries where a(n) has not yet been found, Nov 21 2016 [With 202 new terms, this supersedes an earlier table of Robert G. Wilson v et al.] EXAMPLE For n=4, since 9^5 == 4 (mod 5) and 9^k is not congruent to 4 (mod k) for any k < 5, a(4) = 5. Michael B. Porter, Dec 10 2016 MAPLE a127817 := [seq(0, j=1..nmax)] ; for k from 1 do n := modp(9^k, k) ; if n > 0 and n <= nmax then if op(n, a127817) = 0 then a127817 := subsop(n=k, a127817) ; print( op(1..50, a127817) ) ; fi; fi; od: # R. J. Mathar, Jul 16 2009 MATHEMATICA t = Table[0, {10000}]; k = 1; lst = {}; While[k < 4500000000, a = PowerMod[9, k, k]; If[ a<10001 && t[[a]]==0, t[[a]]=k; Print[{a, k}]]; k++ ]; t CROSSREFS Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127818, A127819, A127820, A127821. Sequence in context: A074067 A110988 A047224 * A199173 A047232 A103557 Adjacent sequences:  A127814 A127815 A127816 * A127818 A127819 A127820 KEYWORD hard,nonn AUTHOR Alexander Adamchuk, Jan 30 2007 EXTENSIONS a(8) <= 2592842671511 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 06 2007 I changed the Mathematica coding to reflect the current limits Robert G. Wilson v, Jul 18 2009 Value for a(8) as suggested by J. K. Crump confirmed by Hagen von Eitzen, Jul 21 2009 Authorship of a-file corrected by R. J. Mathar, Aug 24 2009 STATUS approved

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Last modified October 18 12:18 EDT 2019. Contains 328160 sequences. (Running on oeis4.)