A054018 Squares mentioned in A054017.

9, 1, 16, 9, 25, 16, 25, 49, 16, 1, 64, 121, 36, 81, 64, 169, 64, 36, 100, 225, 64, 36, 121, 36, 169, 49, 361, 225, 1, 144, 441, 441, 144, 256, 400, 196, 64, 441, 1, 144, 361, 64, 400, 441, 729, 64, 196, 144, 729, 100, 841, 729, 25, 400, 256, 1225, 100, 729, 1225

Offset: 1

Author

Asher Auel, Jan 19 2000

Keywords

• nonn

Comments

If Chowla's function of n read (modulo n) is a nonzero square, print this square.

Chowla's function (A048050) = sum of divisors of n except 1 and n.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A048050, A054013, A054017, A054019.

Programs

Mathematica

chowla[n_] := DivisorSigma[1, n] - n - 1; aQ[n_] := (c = chowla[n]) > 0 && IntegerQ @ Sqrt @ Mod[c, n]; Mod[chowla[#], #] & /@ Select[Range[1000], aQ] (* Amiram Eldar, Aug 28 2019 *)