A054019 - OEIS

%I #10 Oct 27 2023 22:00:46

%S 3,1,4,3,5,4,5,7,4,1,8,11,6,9,8,13,8,6,10,15,8,6,11,6,13,7,19,15,1,12,

%T 21,21,12,16,20,14,8,21,1,12,19,8,20,21,27,8,14,12,27,10,29,27,5,20,

%U 16,35,10,27,35,31,30,29,3,12,28,5,1,35,26,10,20,37,12,33,18,43,43,45,22

%N Square roots of A054018.

%H Amiram Eldar, <a href="/A054019/b054019.txt">Table of n, a(n) for n = 1..10000</a>

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

%Y Cf. A048050, A054013, A054017, A054018.

%K nonn

%O 1,1

%A _Asher Auel_, Jan 19 2000