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 A135762 #5 Nov 08 2016 07:45:57
%S A135762 1,3,2,5,4,7,6,8,9,11,10,13,12,14,15,17,16,19,18,20,21,23,22,24,25,26,
%T A135762 27,29,28,31,30,32,33,34,35,37,36,38,39,41,40,43,42,44,45,47,46,48,49,
%U A135762 50,51,53,52,54,55,56,57,59,58,61,60,62,63,64,65,67,66,68,69,71,70,73
%N A135762 Start with sequence of positive integers, then swap a(i) and a(i-1) if a(i) is an odd prime.
%H A135762 G. C. Greubel, <a href="/A135762/b135762.txt">Table of n, a(n) for n = 1..10000</a>
%e A135762 a(1)=1; then
%e A135762 a(2)=3 and a(3)=2 because p=3 is odd prime and p and p-1 are swapped.
%t A135762 r=Range[100];Do[If[PrimeQ[r[[i]]],{r[[i]],r[[i-1]]}={r[[i-1]],r[[i]]}],{i,3,97,2}];r
%Y A135762 Cf. A135761.
%K A135762 nonn
%O A135762 1,2
%A A135762 _Zak Seidov_, Nov 27 2007