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 A239614 #35 Aug 03 2024 19:21:01
%S A239614 1,2,2,4,2,4,2,6,3,4,2,8,2,4,4,8,2,6,2,8,4,4,2,12,3,4,4,8,2,8,2,10,4,
%T A239614 4,4,12,2,4,4,12,2,8,2,8,6,4,2,16,3,6,4,8,2,8,4,12,4,4,2,16,2,4,6,12,
%U A239614 4,8,2,8,4,8,2,18,2,4,6,8,4,8,2,16,5,4,2,16,4,4,4,12,2,12,4,8,4,4,4,20,2,6,6,12,2,8,2,12,8
%N A239614 a(n) = A239611(n) / A079458(n).
%C A239614 Related to Menon's identity. See Conclusions and further work section of the arXiv file linked.
%C A239614 Multiplicative because both A239611 and A079458 are. - _Andrew Howroyd_, Aug 07 2018
%H A239614 Antti Karttunen, <a href="/A239614/b239614.txt">Table of n, a(n) for n = 1..2101</a> (computed from the b-files of A079458 and A239611)
%H A239614 C. Calderón, J. M. Grau, A. Oller-Marcen, and Laszlo Toth, <a href="http://arxiv.org/abs/1403.7878">Counting invertible sums of squares modulo n and a new generalization of Euler totient function</a>, arXiv:1403.7878 [math.NT], 2014.
%F A239614 Conjectures from _Ridouane Oudra_, Jul 22 2024: (Start)
%F A239614 a(n) = A010710(n)*tau(n) - 2*tau(2n) ;
%F A239614 a(2*n) = 2*tau(n) ;
%F A239614 a(2*n+1) = tau(2*n+1). (End)
%t A239614 a239611[n_] := Sum[If[GCD[x^2 + y^2, n] == 1, GCD[x^2 + y^2 - 1, n], 0], {x, 1, n}, {y, 1, n}];
%t A239614 a079458[n_] := Product[{p, e} = pe; Which[p==2, 2^(2e-1), Mod[p, 4]==3, (p^2-1)p^(2e-2), Mod[p, 4]==1, (p-1)^2 p^(2e-2)], {pe, FactorInteger[n]}];
%t A239614 a[1] = 1; a[n_] := a239611[n]/a079458[n];
%t A239614 Array[a, 105] (* _Jean-François Alcover_, Dec 04 2018 *)
%Y A239614 Cf. A239611, A239612, A239613, A239615, A079458, A053191, A227499.
%K A239614 nonn,mult
%O A239614 1,2
%A A239614 _José María Grau Ribas_, Jun 25 2014
%E A239614 More terms from _Antti Karttunen_, Sep 23 2017