A242960 Numbers n such that 7^A000010(n) == 1 (mod n^2).

4, 5, 10, 20, 40, 80, 491531, 983062, 1966124, 2457655, 3932248, 4915310, 6389903, 9339089, 9830620, 12288275, 12779806, 18678178, 19169709, 19661240, 24576550, 25559612, 28017267, 31949515, 37356356, 38339418, 39322480, 46695445, 49153100, 51119224, 56034534

Offset: 1

Author

Felix Fröhlich, May 27 2014

Keywords

• nonn

Links

• Giovanni Resta, Table of n, a(n) for n = 1..425

Crossrefs

Cf. A077816, A242959, A000010. All primes in this sequence are in A123693.

Programs

PARI

for(n=2, 10^9, if(Mod(7, n^2)^(eulerphi(n))==1, print1(n, ", ")))

Extensions

Terms a(23) and beyond from Giovanni Resta, Jan 24 2020