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 A222244 #11 Mar 30 2017 22:42:44
%S A222244 0,1,2,3,9,5,6,7,8,4,10,11,12,13,19,15,16,17,18,14,20,21,22,23,29,25,
%T A222244 26,27,28,24,30,31,32,33,39,35,36,37,38,34,90,91,92,93,99,95,96,97,98,
%U A222244 94,50,51,52,53,59,55,56,57,58,54,60,61,62,63,69,65,66,67,68,64,70,71,72,73,79,75
%N A222244 In the number n, replace all (decimal) digits '4' with '9' and vice versa.
%C A222244 The map which is applied to primes in A171053.
%H A222244 Vincenzo Librandi, <a href="/A222244/b222244.txt">Table of n, a(n) for n = 0..1000</a>
%t A222244 a[n_]:= IntegerDigits[n]/.{4->9, 9->4} // FromDigits; Table[a[n], {n, 0, 80}] (* _Vincenzo Librandi_, Jul 31 2013 *)
%o A222244 (PARI) A222244(n,d=[0, 1, 2, 3, 9, 5, 6, 7, 8, 4])={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 A222244 Cf. A222210-A222254; A171013-A171016, A175770, A171018-A171057.
%K A222244 nonn,base,easy
%O A222244 0,3
%A A222244 _M. F. Hasler_, Feb 13 2013