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 A385148 #22 Jun 24 2025 07:20:38
%S A385148 0,1,6,1,7,15,8,9,11,14,10,55,15,28,54,1,22,17,14,43,66,50,16,64,1,26,
%T A385148 78,63,31,172,20,41,90,32,40,45,50,63,144,56,40,196,26,76,259,64,43,
%U A385148 236,1,65,126,56,64,136,56,134,186,50,34,504,63,117,198,1,64,300,74,70,222,203
%N A385148 a(n) = A001065(A346878(n)).
%C A385148 There are only 2 known fixed points 26 and 296; they are the numbers k such that k = sigma(m) - m where m = sigma(2*k) - 2*k as investigated by _S. I. Dimitrov_. See link.
%H A385148 S. I. Dimitrov, <a href="https://arxiv.org/abs/2408.07387">Generalizations of amicable numbers</a>, arXiv:2408.07387 [math.NT], 2024. See Table 2 p. 7.
%t A385148 f[x_] := DivisorSigma[1, x] - x; Table[Nest[f, 2*n, 2], {n, 120}] (* _Michael De Vlieger_, Jun 19 2025 *)
%o A385148 (PARI) a(n) = my(m=sigma(2*n) - 2*n); sigma(m) - m ;
%Y A385148 Cf. A001065, A346878.
%Y A385148 Cf. A377766 (twice the integers that satisfy a(n)=1).
%Y A385148 Cf. A384411.
%K A385148 nonn
%O A385148 1,3
%A A385148 _Michel Marcus_, Jun 19 2025