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A127818 a(n) = least k such that the remainder when 10^k is divided by k is n. 38

%I

%S 3,14,7,6,35,94,993,46,22963573117,11,15084115509707,22,21,86,99985,

%T 24,221819,82,327,1996,28039,26,169,38,39,74,24257,36,10191082613,65,

%U 49,34,4739,66,99965,188,171,62,3753219157,60,3961,58,87,76,28315,159,10441

%N a(n) = least k such that the remainder when 10^k is divided by k is n.

%H Robert G. Wilson v, <a href="/A127818/a127818.txt">Table of n, a(n) for n = 1..10000 with -1 for large entries where a(n) has not yet been found</a>

%t t = Table[0, {10000} ]; k = 1; While[ k < 4000000000, a = PowerMod[10, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t

%Y Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127819, A127820, A127821.

%K hard,nonn

%O 1,1

%A _Alexander Adamchuk_, Jan 30 2007

%E a(9) <= 22963573117 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 09 2007

%E a(11) <= 15084115509707 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 06 2007

%E a(29) <= 112237795073 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 09 2007

%E a(39) <= 3753219157 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 10 2007

%E Crump's values for a(9), a(11), a(39) confirmed, a(29) = 10191082613 = 16763 * 607951 by _Hagen von Eitzen_, Jul 29 2009

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Last modified November 18 22:50 EST 2019. Contains 329305 sequences. (Running on oeis4.)