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 A370682 #7 Feb 27 2024 01:32:39
%S A370682 1,5,11,19,71,203,271,979,991,2755,5976,6407,7004,8560,9143,33552,
%T A370682 46583,75856,87955,90287,101955,243271,265587,269648,457135,510192,
%U A370682 512783,551172,559656,1804555,1917639,2902175,4339952,6783820,9842748,10463980,17428447,21677503
%N A370682 Numbers k such that A370681(k) = A370681(k+1).
%H A370682 Amiram Eldar, <a href="/A370682/b370682.txt">Table of n, a(n) for n = 1..120</a>
%e A370682 5 is a term since A370681(5) = A370681(6) = 4.
%t A370682 s[n_] := Module[{d = Reverse[Select[Divisors[n], CoprimeQ[#, n/#] &]]}, Total[(-1)^(Range[Length[d]] + 1)*d]]; Select[Range[10^5], s[#] == s[# + 1] &]
%o A370682 (PARI) s(n) = {my(d = Vecrev(select(x->(gcd(x, n/x) == 1), divisors(n)))); sum(i=1, #d, (-1)^(i+1)*d[i]);}
%o A370682 lista(nmax) = {my(s1 = s(1), s2); for(n = 2, nmax, s2 = s(n); if(s1 == s2, print1(n-1,", ")); s1=s2);}
%Y A370682 Cf. A064125, A333261, A370681.
%K A370682 nonn
%O A370682 1,2
%A A370682 _Amiram Eldar_, Feb 26 2024