

A119678


a(n) = least k such that the remainder when 4^k is divided by k is n.


46



3, 14, 137243, 5, 6821, 10, 57, 124, 35, 18, 2791496231, 244, 51, 505, 199534799, 20, 30271293169, 49, 45, 236, 399531841, 42, 533, 25, 39, 50, 352957, 36, 995, 98, 33, 112, 47503, 55, 42345881, 44, 2981, 289, 805, 78, 1019971289, 25498, 2121, 212
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OFFSET

1,1


COMMENTS

a(n) > n.
Numbers n>1 such that a(n1) = n are listed in A015950.
a(87) > 10^14.


LINKS

Ryan Propper, Table of n, a(n) for n = 1..82, Feb 21 2007
Robert G. Wilson v, Table of n, a(n) for n = 1..10000 with 1 for those entries where a(n) has not yet been found


FORMULA

a(5^k1) = 5^k.


MATHEMATICA

Do[k = 1; While[PowerMod[4, k, k] != n, k++ ]; Print[k], {n, 30}]
t = Table[0, {10000} ]; k = 1; While[ k < 5000000000, a = PowerMod[4, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t


CROSSREFS

Cf. A015950, A036236, A078457, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127820, A127821.
Sequence in context: A268158 A050645 A048568 * A096682 A009215 A274078
Adjacent sequences: A119675 A119676 A119677 * A119679 A119680 A119681


KEYWORD

nonn


AUTHOR

Ryan Propper, Jun 12 2006


EXTENSIONS

a(11) <= 2791496231, a(17) <= 140631956671, a(53) <= 52134328061 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 10 2007
a(11) = 2791496231 from Robert G. Wilson v, Feb 11 2007; confirmed by Ryan Propper, Feb 15 2007
Extended through n = 82 by Ryan Propper, Feb 21 2007
Search limits in the Mathematica coding is expanded by Robert G. Wilson v, Jul 14 2009
Link corrected by R. J. Mathar, Jul 24 2009
a(83) = 3085807457009 = 113 * 331 * 82501603 from Hagen von Eitzen, Jul 27 2009


STATUS

approved



