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 A335440 #16 Jun 15 2020 03:17:21 %S A335440 1,8,18,50,60,64,81,98,105,144,225,242,308,338,400,429,441,480,512, %T A335440 546,578,625,648,722,756,784,884,935,969,1058,1089,1122,1152,1190, %U A335440 1225,1235,1428,1430,1458,1463,1485,1521,1547,1682,1748,1800,1820,1922,1936,2001 %N A335440 Lexicographically earliest sequence of distinct positive terms such that two distinct terms differ by at least 3 prime factors. %C A335440 In other words, for any distinct m and n, let a(m)/a(n) = u/v in reduced form, then bigomega(u) + bigomega(v) >= 3 (where bigomega corresponds to A001222(n), the number of distinct prime factors of n with multiplicity). %C A335440 The variant where distinct terms differ by at least 1 prime factor simply corresponds to the positive numbers. %C A335440 The variant where distinct terms differ by at least 2 prime factors corresponds to A028260. %C A335440 No term is prime nor the square of a prime. %C A335440 This sequence has similarities with A075926 and A333568; here we consider prime factors, there digits. %H A335440 Rémy Sigrist, <a href="/A335440/b335440.txt">Table of n, a(n) for n = 1..10000</a> %H A335440 Rémy Sigrist, <a href="/A335440/a335440.txt">C program for A335440</a> %e A335440 The first terms, alongside their p-adic valuations for p = 2..11 (with dots instead of zeros), are: %e A335440 n a(n) v2 v3 v5 v7 v11 %e A335440 -- ---- -- -- -- -- --- %e A335440 1 1 . . . . . %e A335440 2 8 3 . . . . %e A335440 3 18 1 2 . . . %e A335440 4 50 1 . 2 . . %e A335440 5 60 2 1 1 . . %e A335440 6 64 6 . . . . %e A335440 7 81 . 4 . . . %e A335440 8 98 1 . . 2 . %e A335440 9 105 . 1 1 1 . %e A335440 10 144 4 2 . . . %e A335440 11 225 . 2 2 . . %e A335440 12 242 1 . . . 2 %e A335440 13 308 2 . . 1 1 %o A335440 (C) See Links section. %Y A335440 Cf. A001222, A028260, A075926, A333568. %K A335440 nonn %O A335440 1,2 %A A335440 _Rémy Sigrist_, Jun 10 2020