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