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 A241978 Numbers n such that 6^phi(n) == 1 (modulo n^2), where phi(n) is Euler's totient function. 5
 66161, 330805, 534851, 2674255, 3152573, 10162169, 13371275, 50810845, 54715147, 129255493, 148170931, 254054225, 273575735, 301121113, 383006029, 646277465, 1289402357, 1505605565, 1915030145, 3228193673, 3407931413, 5721301147, 6075008171, 7528027825 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(17) > 10^9. LINKS Giovanni Resta, Table of n, a(n) for n = 1..95 (terms < 10^14) MATHEMATICA Select[Range[65*10^7], PowerMod[6, EulerPhi[#], #^2]==1&] (* Harvey P. Dale, Jan 20 2020 *) PROG (PARI) for(n=2, 1e9, if(Mod(6, n^2)^(eulerphi(n))==1, print1(n, ", "))) CROSSREFS Cf. A000010, A077816, A212583, A242958, A242959, A242960, A241977, A245529. Sequence in context: A254192 A254185 A253797 * A212583 A156424 A092376 Adjacent sequences: A241975 A241976 A241977 * A241979 A241980 A241981 KEYWORD nonn AUTHOR Felix Fröhlich, Aug 10 2014 EXTENSIONS Terms a(17) and beyond from Giovanni Resta, Jan 24 2020 STATUS approved

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Last modified July 25 14:52 EDT 2024. Contains 374611 sequences. (Running on oeis4.)