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 A222241 #11 Mar 31 2017 00:17:02
%S A222241 0,1,2,3,6,5,4,7,8,9,10,11,12,13,16,15,14,17,18,19,20,21,22,23,26,25,
%T A222241 24,27,28,29,30,31,32,33,36,35,34,37,38,39,60,61,62,63,66,65,64,67,68,
%U A222241 69,50,51,52,53,56,55,54,57,58,59,40,41,42,43,46,45,44,47,48,49,70,71,72,73,76,75
%N A222241 In the number n, replace all (decimal) digits '4' with '6' and vice versa.
%C A222241 The map which is applied to primes in A171032.
%H A222241 Vincenzo Librandi, <a href="/A222241/b222241.txt">Table of n, a(n) for n = 0..1000</a>
%t A222241 a[n_]:= IntegerDigits[n]/.{4->6, 6->4} // FromDigits; Table[a[n], {n, 0, 80}] (* _Vincenzo Librandi_, Jul 31 2013 *)
%o A222241 (PARI) A222241(n,d=[0, 1, 2, 3, 6, 5, 4, 7, 8, 9])={sum(i=1,#n=digits(n),d[n[i]+1]*10^(#n-i),!n*d[1])} \\ N.B.: digits(0)=[] in PARI (v.2.6)
%Y A222241 Cf. A222210-A222254; A171013-A171016, A175770, A171018-A171057.
%K A222241 nonn,base,easy
%O A222241 0,3
%A A222241 _M. F. Hasler_, Feb 13 2013