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 A262590 #9 Oct 19 2023 08:49:52 %S A262590 0,2,6,18,62,210,728,2570,9198,33288,121574,447394,1657008,6170930, %T A262590 23091222,86767016,327235610,1238188770,4698767640 %N A262590 Sets with a congruence property. %H A262590 Alexander Rosa and Štefan Znám, <a href="/A002703/a002703.pdf">A combinatorial problem in the theory of congruences (Russian with English summary)</a>, Mat.-Fys. Casopis Sloven. Akad. Vied 15 1965 49-59. [Annotated scanned copy.] %H A262590 Alexander Rosa and Štefan Znám, <a href="/A002703/a002703_1.pdf">A remark on a combinatorial problem (Russian with English summary)</a>, Mat.-Fyz. Casopis Sloven. Akad. Vied 15 1965 313-316. [Annotated scanned copy] See Table 1. %F A262590 See Maple code in A002705. %K A262590 nonn %O A262590 3,2 %A A262590 _R. J. Mathar_, Oct 21 2015