%I #10 Oct 27 2023 22:00:46
%S 14,20,39,40,46,55,80,94,100,104,117,130,155,158,183,190,200,203,291,
%T 292,295,299,320,323,334,416,430,446,464,475,488,530,539,549,567,579,
%U 583,638,650,695,718,799,873,878,890,943,955,959,964,979,1030,1118
%N Chowla's function of n modulo n is a square (excluding 0's).
%C Chowla's function (A048050) = sum of divisors of n except 1 and n.
%H Amiram Eldar, <a href="/A054017/b054017.txt">Table of n, a(n) for n = 1..10000</a>
%t aQ[n_] := (c = DivisorSigma[1, n] - n - 1) > 0 && IntegerQ @ Sqrt @ Mod[c, n]; Select[Range[1000], aQ] (* _Amiram Eldar_, Aug 28 2019 *)
%Y Cf. A048050, A054013, A054018.
%K nonn
%O 1,1
%A _Asher Auel_, Jan 19 2000