3,1

a(11)-a(13) = {18659, 120593747, 13757837}. a(n) is currently unknown for n = {9, 10, ...}.

a(14)-a(15) = {17651, 17149}. a(18)-a(23) = {407, 39959, 559, 581831, 305197, 235}. a(28)-a(29) = {240055, 11227}. a(32) = 75197. - Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 17 2007

a(16) = A128156(15) = 16584420001 found by Ryan Propper Feb 27 2007.

Robert G. Wilson v, Table of n, a(n) for n = 2..1000 . [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 15 2009]

a(3) = A078457(2) = 2929.

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}] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 15 2009]

Cf. A128148, A128150 = least k such that n^k (mod k) = (n-1)^2. Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127820, A127821.

Cf. A128172 = least k such that n^k (mod k) = n+1. Cf. A128154, A128155, A128156, A128157, A128158, A128159, A128160.

Cf. A128361, A128362, A128363, A128364, A128365, A128366, A128367, A128368, A128369, A129370, A128371, A128372.

Sequence in context: A127489 A054831 A127490 this_sequence A054832 A068290 A096628

Adjacent sequences: A128146 A128147 A128148 this_sequence A128150 A128151 A128152

hard,nonn

Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 16 2007

a(6) = A127816(5) = 4021227877 found by Ryan Propper Feb 21 2007.

More terms from Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 28 2007

a(9), a(10) from Hagen von Eitzen (math(AT)von-eitzen.de), Jul 31 2009

More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 15 2009