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 A222234 #11 Mar 31 2017 00:20:38
%S A222234 0,1,2,4,3,5,6,7,8,9,10,11,12,14,13,15,16,17,18,19,20,21,22,24,23,25,
%T A222234 26,27,28,29,40,41,42,44,43,45,46,47,48,49,30,31,32,34,33,35,36,37,38,
%U A222234 39,50,51,52,54,53,55,56,57,58,59,60,61,62,64,63,65,66,67,68,69,70,71,72,74,73,75
%N A222234 In the number n, replace all (decimal) digits '3' with '4' and vice versa.
%C A222234 The map which is applied to primes in A171022.
%H A222234 Vincenzo Librandi, <a href="/A222234/b222234.txt">Table of n, a(n) for n = 0..1000</a>
%t A222234 a[n_]:= IntegerDigits[n]/.{3->4, 4->3} // FromDigits; Table[a[n], {n, 0, 80}] (* _Vincenzo Librandi_, Jul 30 2013 *)
%o A222234 (PARI) A222234(n,d=[0,1,2,4,3,5,6,7,8,9])=sum(i=1,#n=digits(n),d[n[i]+1]*10^(#n-i)) \\ gives correct value for n=0 iff d[1]=0, since digits(0)=[] in PARI (v.2.6)
%Y A222234 Cf. A222210-A222254; A171013-A171016, A175770, A171018-A171057.
%K A222234 nonn,base,easy
%O A222234 0,3
%A A222234 _M. F. Hasler_, Feb 12 2013