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 A288171 #18 Jun 16 2017 22:22:03 %S A288171 1,2,3,2310,1155,770,4,6,9,1365,385,910,8,12,11,1785,455,210,10,18,13, %T A288171 231,595,330,20,22,7,273,105,390,30,26,14,77,165,195,60,28,34,91,255, %U A288171 285,66,38,42,35,315,55,78,44,84,70,345,65,33,52,102,130,357,95 %N A288171 Lexicographically earliest sequence of distinct positive terms such that, for any n > 0, a(n)*a(n+3) has at least 5 distinct prime factors. %C A288171 This sequence is a permutation of the natural numbers, with inverse A288800. %C A288171 See also A288164 for similar sequences. %C A288171 Conjecturally, a(n) ~ n. %H A288171 Rémy Sigrist, <a href="/A288171/b288171.txt">Table of n, a(n) for n = 1..25000</a> %H A288171 Rémy Sigrist, <a href="/A288171/a288171.txt">C++ program for A288171</a> %H A288171 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %e A288171 The first terms, alongside the primes p dividing a(n)*a(n+3), are: %e A288171 n a(n) p %e A288171 -- ---- -------------- %e A288171 1 1 2, 3, 5, 7, 11 %e A288171 2 2 2, 3, 5, 7, 11 %e A288171 3 3 2, 3, 5, 7, 11 %e A288171 4 2310 2, 3, 5, 7, 11 %e A288171 5 1155 2, 3, 5, 7, 11 %e A288171 6 770 2, 3, 5, 7, 11 %e A288171 7 4 2, 3, 5, 7, 13 %e A288171 8 6 2, 3, 5, 7, 11 %e A288171 9 9 2, 3, 5, 7, 13 %e A288171 10 1365 2, 3, 5, 7, 13 %e A288171 11 385 2, 3, 5, 7, 11 %e A288171 12 910 2, 5, 7, 11, 13 %e A288171 13 8 2, 3, 5, 7, 17 %e A288171 14 12 2, 3, 5, 7, 13 %e A288171 15 11 2, 3, 5, 7, 11 %e A288171 16 1785 2, 3, 5, 7, 17 %e A288171 17 455 2, 3, 5, 7, 13 %e A288171 18 210 2, 3, 5, 7, 13 %e A288171 19 10 2, 3, 5, 7, 11 %e A288171 20 18 2, 3, 5, 7, 17 %Y A288171 Cf. A288164, A288800 (inverse). %K A288171 nonn,look %O A288171 1,2 %A A288171 _Rémy Sigrist_, Jun 16 2017