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 A380222 #19 Feb 13 2025 14:17:42 %S A380222 2,6,6,12,18,30,42,60,90,126,210,252,420,630,840,1260,1680,2730,3276, %T A380222 5460,8190,10920,16380,21840,32760,40950,65520,90090,120120,180180, %U A380222 253890,360360,507780,720720,1015560,1332240,2031120,2792790,3996720,5585580 %N A380222 Highest integer k such that the multiplicative group modulo k is a subgroup of the symmetric group S_n. %C A380222 a(n) is the highest k for which A380827(k) <= n. %H A380222 Asher Gray, <a href="/A380222/b380222.txt">Table of n, a(n) for n = 1..5000</a> %H A380222 Asher Gray, <a href="https://github.com/thegraycuber/highest-modulus-within-S_n">Highest modulus within S_n</a>, Github repository. %e A380222 a(2) = 6 because (Z/6Z)* is a subgroup of S_2 (isomorphic to it in fact) and there is no modulus k with k > 6 and (Z/kZ)* a subgroup of S_2. %Y A380222 Cf. A380827, A034891. %K A380222 nonn %O A380222 1,1 %A A380222 _Asher Gray_, Jan 17 2025