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A130421 Numbers n such that 4^n == 2 (mod n). 7
1, 2, 14, 1022, 20066, 80519, 107663, 485918, 1284113, 1510313, 2531678, 3677198, 3933023, 4557713, 8277458, 8893262, 21122318, 24849833, 26358638, 39852014, 42448478, 71871113, 76712318, 80646143, 98058097, 104832833, 106694033, 131492498, 144322478, 146987033, 164360606, 168204191, 175126478, 176647378, 188997463, 196705598 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The odd terms multiplied by 2 form A006935. - Max Alekseyev, Jun 06 2014

Some terms above 10^15: 26435035805519327, 158975398896178078, 64044049390757098943, 1063423126446412987081943, 1091220919655042176978844783, 81074850280355100090334498663, 6317483763950169936179578094903, 5672799393875320397186007124651847, 170923900137537174138295268515194974, 195746953975871672436191077726091399305155458, 325665752547333314939363628501536024940097079718953, 953533053776414279913696071891872697927468471633033, 85791212788381063775490416118630897060666265030605503, 334519297382630382793758729321508383611586565722054114034741260213364710519401967713. - Max Alekseyev, Jun 18 2014

LINKS

Max Alekseyev, Table of n, a(n) for n = 1..2617 (all terms below 10^15)

MATHEMATICA

Join[{1, 2}, Select[Range[107000000], PowerMod[4, #, #]==2&]] (* Harvey P. Dale, Jun 13 2013 *)

CROSSREFS

Cf. A130422.

Sequence in context: A225163 A319540 A190634 * A227403 A156736 A334247

Adjacent sequences:  A130418 A130419 A130420 * A130422 A130423 A130424

KEYWORD

nonn

AUTHOR

Jon E. Schoenfield, May 26 2007

EXTENSIONS

Terms a(28) onward from Max Alekseyev, Jun 18 2014

b-file corrected by Max Alekseyev, Oct 09 2016

STATUS

approved

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Last modified July 10 00:05 EDT 2020. Contains 335570 sequences. (Running on oeis4.)