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 A067003 #11 Jul 13 2019 17:52:58
%S A067003 1,1,2,3,4,1,5,6,7,2,8,3,9,4,5,10,11,6,12,7,8,9,13,10,14,11,15,12,16,
%T A067003 1,17,18,13,14,15,16,19,17,18,19,20,2,21,20,21,22,22,23,23,24,25,26,
%U A067003 24,27,28,29,30,31,25,3,26,32,33,27,34,4,28,35,36,5,29,37,30,38,39,40,41
%N A067003 Number of numbers <= n with same number of distinct prime factors as n.
%H A067003 Rémy Sigrist, <a href="/A067003/b067003.txt">Table of n, a(n) for n = 1..10000</a>
%F A067003 a(A002110(n)) = 1.
%e A067003 a(11)=8 since 2,3,4,5,7,8,9,11 each have one distinct prime factor. a(12)=3 since 6,10,12 each have two distinct prime factors.
%e A067003 From _Gus Wiseman_, Dec 28 2018: (Start)
%e A067003 Column n lists the a(n) positive integers less than or equal to n with the same number of distinct prime factors as n:
%e A067003 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
%e A067003 ---------------------------------------------------------------------
%e A067003 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
%e A067003 2 3 4 5 7 8 6 9 10 11 12 14 13 16 15 17 18
%e A067003 2 3 4 5 7 8 6 9 10 12 11 13 14 16 15
%e A067003 2 3 4 5 7 8 6 10 9 11 12 13 14
%e A067003 2 3 4 5 7 6 8 9 10 11 12
%e A067003 2 3 4 5 7 8 6 9 10
%e A067003 2 3 4 5 7 8 6
%e A067003 2 3 4 5 7
%e A067003 2 3 4 5
%e A067003 2 3 4
%e A067003 2 3
%e A067003 2
%e A067003 (End)
%t A067003 Table[Length[Select[Range[n],PrimeNu[#]==PrimeNu[n]&]],{n,100}] (* _Gus Wiseman_, Dec 28 2018 *)
%o A067003 (PARI) a(n) = my(nb = #factor(n)~); sum(k=1, n, #factor(k)~ == nb); \\ _Michel Marcus_, Jul 13 2019
%Y A067003 Positions of 1's are A002110.
%Y A067003 Cf. A001221, A008479, A058933, A067004. Inverse of A000961, A007774, A033992, A033993, A051270 etc.
%Y A067003 Cf. A000010, A006049, A061142, A294277, A294278, A302242, A322837, A322841.
%K A067003 nonn,look
%O A067003 1,3
%A A067003 _Henry Bottomley_, Dec 21 2001