A241978 Numbers n such that 6^phi(n) == 1 (modulo n^2), where phi(n) is Euler's totient function.

66161, 330805, 534851, 2674255, 3152573, 10162169, 13371275, 50810845, 54715147, 129255493, 148170931, 254054225, 273575735, 301121113, 383006029, 646277465, 1289402357, 1505605565, 1915030145, 3228193673, 3407931413, 5721301147, 6075008171, 7528027825

Offset: 1

Author

Felix Fröhlich, Aug 10 2014

Keywords

• nonn

Comments

a(17) > 10^9.

Links

• Giovanni Resta, Table of n, a(n) for n = 1..95 (terms < 10^14)

Crossrefs

Cf. A000010, A077816, A212583, A242958, A242959, A242960, A241977, A245529.

Programs

Mathematica

Select[Range[65*10^7],PowerMod[6,EulerPhi[#],#^2]==1&] (* Harvey P. Dale, Jan 20 2020 *)

PARI

for(n=2, 1e9, if(Mod(6, n^2)^(eulerphi(n))==1, print1(n, ", ")))

Extensions

Terms a(17) and beyond from Giovanni Resta, Jan 24 2020