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 A387290 #22 Sep 03 2025 17:26:40 %S A387290 241920,483840,725760,967680,1209600,1451520,1693440,1935360,2177280, %T A387290 2419200,2903040,3386880,3628800,3870720,4354560,4838400,5080320, %U A387290 5253120,5806080,6048000,6531840,6773760,6967296,7257600,7741440,7879680,8467200,8709120,9123840,9676800 %N A387290 Numbers k such that there exist three numbers x, y and z such that k = psi(x) = psi(y) = psi(z) = x + y + z. %C A387290 The numbers x, y and z form a psi-amicable triple. %H A387290 S. I. Dimitrov, <a href="https://arxiv.org/abs/2508.02318">On psi-amicable numbers and their generalizations</a>, arXiv:2508.02318 [math.NT], 2025. %e A387290 241920 is in the sequence since 241920 = psi(79170) = psi(80850) = psi(81900) = 79170 + 80850 + 81900. %Y A387290 Cf. A001615, A137231, A385852, A386901, A386933. %K A387290 nonn,new %O A387290 1,1 %A A387290 _S. I. Dimitrov_, Aug 25 2025