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 A334625 #17 Sep 25 2020 04:31:04
%S A334625 3,3,3,3,3,3,9,9,9,9,12,12,15,15,15,15,18,18,21,21,21,21,24,24,27,27,
%T A334625 27,27,30,30,33,33,33,33,36,36,39,39,39,39,42,42,45,45,45,45,48,48,51,
%U A334625 51,51,51,54,54,57,57,57,57,60,60
%N A334625 Maximal size of a subset T of S = {1,2,...,n} with a cyclic arrangement of T such that any three neighbors can be reordered in an arithmetic progression.
%H A334625 Fausto A. C. Cariboni, <a href="/A334625/b334625.txt">Table of n, a(n) for n = 3..111</a>
%H A334625 Fausto A. C. Cariboni, <a href="/A334625/a334625.txt">Examples of cyclic arrangements for a(3)-a(111)</a>
%F A334625 Conjectures from _Colin Barker_, Sep 10 2020: (Start)
%F A334625 G.f.: 3*x^3*(1 + x^6 + x^10 - x^12) / ((1 - x)^2*(1 + x)*(1 - x + x^2)*(1 + x + x^2)).
%F A334625 a(n) = a(n-1) + a(n-6) - a(n-7) for n>15.
%F A334625 (End)
%Y A334625 Cf. A336351.
%K A334625 nonn
%O A334625 3,1
%A A334625 _Fausto A. C. Cariboni_, Sep 09 2020