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 A380921 #5 Feb 08 2025 22:43:50 %S A380921 1,2,6,15,28,40,66,91,120,144,170,204,252,299,330,374,414,475,522,570, %T A380921 616,667,720,798,840,910,986,1050,1116,1189,1274,1333,1395,1480,1554, %U A380921 1628,1692,1776,1850,1924,2016,2107,2178,2244,2356,2432,2511,2624,2697,2808 %N A380921 Least k such that A380783(k) = n. %F A380921 A380783(a(n)) = n. %Y A380921 Cf. A380783. %K A380921 nonn %O A380921 1,2 %A A380921 _Pontus von Brömssen_, Feb 08 2025