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 A064505 #11 Sep 19 2018 21:43:37
%S A064505 1,4,9,2,25,6,49,8,3,10,121,12,169,14,15,16,289,18,361,20,21,22,529,
%T A064505 24,5,26,27,28,841,30,961,32,33,34,35,36,1369,38,39,40,1681,42,1849,
%U A064505 44,45,46,2209,48,7,50,51,52,2809,54,55,56,57,58,3481,60,3721,62,63,64,65,66
%N A064505 Interchange primes and their squares.
%C A064505 a(a(n)) = n, self-inverse permutation for the natural numbers.
%H A064505 Zak Seidov, <a href="/A064505/b064505.txt">Table of n, a(n) for n = 1..1000.</a>
%H A064505 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%t A064505 s=Range[1000]; Do[p=Prime[n];s[[p]]=p^2,{n,PrimePi[1000]}]; Do[p=Prime[n];s[[p^2]]=p,{n,PrimePi[Sqrt@1000]}];s (* _Zak Seidov_, Jun 29 2008 *)
%K A064505 nonn
%O A064505 1,2
%A A064505 _Reinhard Zumkeller_, Oct 16 2001