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 A358201 #8 Jan 16 2023 09:10:46
%S A358201 1,2,3,4,7,6,8,5,9,13,10,12,14,15,16,31,18,20,22,24,26,28,30,32,21,27,
%T A358201 33,34,36,35,39,38,40,25,42,44,45,46,48,50,51,52,49,54,55,56,57,58,60,
%U A358201 62,63,64,127,66,68,70,72,74,76,78,80,82,84,86,88,90,92,94,96,98,100,102,104,106,108
%N A358201 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest positive number not occurring earlier that shares a factor with sigma(max_{k=1..n-1}a(k)).
%C A358201 The sequence is conjectured to be a permutation of the positive integers. In the first 150000 terms the fixed points are 1, 2, 3, 4, 6, 9, 12, 93, 6003, 6881, 16269, 100707, 114839, 116999. It is likely more exist.
%H A358201 Scott R. Shannon, <a href="/A358201/a358201.png">Image of the first 150000 terms</a>. The green line is a(n) = n.
%e A358201 a(9) = 9 as sigma(max_{k=1..8}a(k)) = sigma(8) = A000203(8) = 15, and 9 is the smallest unused number that shares a factor with 15.
%Y A358201 Cf. A000203, A358176, A358082, A064413, A356851, A356430, A354960.
%K A358201 nonn,look
%O A358201 1,2
%A A358201 _Scott R. Shannon_, Nov 03 2022