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 A342021 #24 Feb 14 2025 08:26:44 %S A342021 5,8,41,47057 %N A342021 Numbers k such that A003415(sigma(k)) = k, where A003415 is the arithmetic derivative, and sigma is the sum of divisors of n. %C A342021 a(5) > 2^33, if it exists. %C A342021 Terms of this sequence and A230165 group into pairs (m, sigma(m)), where m is a term of this sequence and sigma(m) is a term of A230165. - _Max Alekseyev_, Feb 13 2025 %F A342021 a(n) = A003415(A230165(n)). - _Max Alekseyev_, Feb 13 2025 %Y A342021 Fixed points of A342925. %Y A342021 Positions of 0's in A342926. %Y A342021 Subsequence of A343217. %Y A342021 Cf. A000203, A003415, A229342, A230164, A230165, A347889. %K A342021 nonn,more,hard %O A342021 1,1 %A A342021 _Antti Karttunen_, Apr 08 2021