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 A066249 #12 Mar 19 2025 08:35:36
%S A066249 3,1,5,2,7,4,8,6,9,10,11,12,13,16,14,18,15,22,17,28,19,30,20,36,21,40,
%T A066249 23,42,24,46,25,52,26,58,27,60,29,66,31,70,32,72,33,78,34,82,35,88,37,
%U A066249 96,38,100,39,102,41,106,43,108,44,112,45,126,47,130,48,136,49,138,50
%N A066249 Inverse permutation to A066248.
%C A066249 Permutation of natural numbers.
%H A066249 Amiram Eldar, <a href="/A066249/b066249.txt">Table of n, a(n) for n = 1..10000</a>
%H A066249 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>.
%F A066249 a(n) = (if n is even then A000040(n/2) else A002808((n+1)/2)) - 1.
%t A066249 seq[nmax_] := Module[{p = Prime[Range[nmax]]}, Riffle[Take[Complement[Range[2, p[[-1]]], p] - 1, Length[p]], p - 1]]; seq[35] (* _Amiram Eldar_, Mar 19 2025 *)
%Y A066249 Cf. A066248, A000040, A002808, A066251, A066253.
%K A066249 nonn
%O A066249 1,1
%A A066249 _Reinhard Zumkeller_, Dec 09 2001