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 A207801 #15 May 01 2016 02:44:42
%S A207801 1,2,3,4,5,6,9,8,7,10,15,12,25,14,21,16,11,18,27,20,35,22,33,24,49,26,
%T A207801 39,28,55,30,45,32,13,34,51,36,65,38,57,40,77,42,63,44,85,46,69,48,
%U A207801 121,50,75,52,95,54,81,56,91,58,87,60,115,62,93,64,17,66,99,68,125,70,105,72,119,74
%N A207801 Permutation of positive numbers. See comments.
%C A207801 a(1)=1; on places 2,4,6,8,... we put the same numbers, i.e., numbers with the least prime divisor p_1=2; on places 3,7,11,15,... we put numbers with the least prime divisor p_2=3; on places 5,13,21,29,... we put numbers with the least prime divisor p_3=5; etc.
%C A207801 For general description of the order, see comment in A207790.
%H A207801 Ivan Neretin, <a href="/A207801/b207801.txt">Table of n, a(n) for n = 1..8192</a>
%F A207801 For n>1, a(n) = A083140(1+A209268(n-1)). Equivalently, a(n) = A083221(1+A249725(n-1)). - _Ivan Neretin_, Apr 30 2016
%t A207801 a = Array[1 &, mx = 74]; cnt = mx - 1; offs = Table[2^(i - 1) + 1, {i, 1, mx}]; n = 1; While[cnt > 0, n++; idx = PrimePi[FactorInteger[n][[1, 1]]]; pos = offs[[idx]]; If[pos > mx, Continue[]]; offs[[idx]] += 2^idx; a[[pos]] = n; cnt--]; a (* _Ivan Neretin_, May 06 2015 *)
%Y A207801 Cf. A207790, A207800.
%K A207801 nonn
%O A207801 1,2
%A A207801 _Vladimir Shevelev_ and _Peter J. C. Moses_, Feb 20 2012