A254329 Numbers n such that all x^2 mod n are prime powers (including 0 and 1).

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 14, 16, 20, 32

Offset

1,2

Links

Table of n, a(n) for n=1..15.

Mathematica

f[n_] := Mod[Range[n]^2, n]; Select[Range@ 10000, AllTrue[f@ #, Length@ FactorInteger[#] == 1 &] &] (* AllTrue function introduced with Version 10; Michael De Vlieger, Jan 29 2015 *)

Prog

(PARI) is(n)=for(i=2, 9, if(!isprimepower(i^2%n) && i^2%n>1, return(0))); 1 \\ Charles R Greathouse IV, Jan 30 2015

Crossrefs

Cf. A065428, A254328.

Sequence in context: A252996 A252495 A182175 * A128870 A355620 A256476

Adjacent sequences: A254326 A254327 A254328 * A254330 A254331 A254332

Keyword

nonn,fini,full

Author

Joerg Arndt, Jan 28 2015

Status

approved