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 A026421 #15 Feb 08 2025 14:19:11
%S A026421 3,4,5,6,7,8,9,10,11,13,14,16,17,19,22,23,25,26,29,31,34,37,38,41,43,
%T A026421 46,47,49,53,58,59,61,62,67,71,73,74,79,81,82,83,86,89,94,97,101,103,
%U A026421 105,106,107,108,109,113,118,120,121,122,127,131
%N A026421 a(n) = least positive integer > a(n-1) and not a(i)*a(j) for 1<=i<j<=n, with initial terms 3,4.
%H A026421 Ivan Neretin, <a href="/A026421/b026421.txt">Table of n, a(n) for n = 1..1000</a>
%F A026421 a(n) = A026417(n+1). - _R. J. Mathar_, May 28 2008
%t A026421 a = {3, 4}; used = {a[[1]]*a[[2]]}; Do[k = a[[-1]] + 1; While[MemberQ[used, k], k++]; used = Union[used, k*a]; AppendTo[a, k], {n, 3, 60}]; a (* _Ivan Neretin_, Mar 07 2016 *)
%Y A026421 Cf. A026416 and references therein.
%K A026421 nonn
%O A026421 1,1
%A A026421 _Clark Kimberling_
%E A026421 Name clarified by _Robert C. Lyons_, Feb 08 2025