A242959 Numbers n such that 5^A000010(n) == 1 (mod n^2).

2, 20771, 40487, 41542, 80974, 83084, 161948, 643901, 1255097, 1287802, 1391657, 1931703, 2510194, 2575604, 2783314, 3765291, 3863406, 4174971, 5020388, 5151208, 5566628, 7530582, 7726812, 8349942, 10040776, 11133256, 15061164, 15308227, 15453624, 16699884

Offset: 1

Author

Felix Fröhlich, May 27 2014

Keywords

• nonn

Links

• Giovanni Resta, Table of n, a(n) for n = 1..479 (terms < 10^15, first 75 terms from Felix Fröhlich)

Crossrefs

Cf. A077816, A242958, A242960.

If a(n) is prime, then a(n) is in A123692.

Programs

Mathematica

Select[Range[167*10^5],PowerMod[5,EulerPhi[#],#^2]==1&] (* Harvey P. Dale, Jun 02 2020 *)

PARI

for(n=2, 10^9, if(Mod(5, n^2)^(eulerphi(n))==1, print1(n, ", ")))