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 A338444 #13 Aug 23 2024 15:55:33 %S A338444 1,2,6,3,5,10,14,7,11,22,26,13,15,30,34,17,19,38,42,21,23,46,58,29,31, %T A338444 62,66,33,35,70,74,37,39,78,82,41,43,86,94,47,51,102,106,53,55,110, %U A338444 114,57,59,118,122,61,65,130,134,67,69,138,142,71,73,146,154,77 %N A338444 Lexicographically earliest sequence of distinct squarefree numbers such that for any prime p, any run of consecutive multiples of p has length exactly 2. %C A338444 This sequence is a squarefree variant of A280864. %C A338444 Conjecture: this sequence is a permutation of the squarefree numbers (A005117). %H A338444 Rémy Sigrist, <a href="/A338444/b338444.txt">Table of n, a(n) for n = 1..10000</a> %H A338444 Rémy Sigrist, <a href="/A338444/a338444.txt">C program for A338444</a> %e A338444 The first terms, alongside their prime factors, are: %e A338444 n a(n) Prime factors %e A338444 -- ---- ------------- %e A338444 1 1 %e A338444 2 2 2 %e A338444 3 6 2 3 %e A338444 4 3 3 %e A338444 5 5 5 %e A338444 6 10 2 5 %e A338444 7 14 2 7 %e A338444 8 7 7 %e A338444 9 11 11 %e A338444 10 22 2 11 %e A338444 11 26 2 13 %e A338444 12 13 13 %e A338444 13 15 3 5 %e A338444 14 30 2 3 5 %e A338444 15 34 2 17 %e A338444 16 17 17 %o A338444 (C) // See Links section. %Y A338444 Cf. A005117, A280864, A338441. %K A338444 nonn %O A338444 1,2 %A A338444 _Rémy Sigrist_, Oct 28 2020