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 A222246 #10 Mar 30 2017 22:41:40
%S A222246 0,1,2,3,4,7,6,5,8,9,10,11,12,13,14,17,16,15,18,19,20,21,22,23,24,27,
%T A222246 26,25,28,29,30,31,32,33,34,37,36,35,38,39,40,41,42,43,44,47,46,45,48,
%U A222246 49,70,71,72,73,74,77,76,75,78,79,60,61,62,63,64,67,66,65,68,69,50,51,52,53,54,57
%N A222246 In the number n, replace all (decimal) digits '5' with '7' and vice versa.
%C A222246 The map which is applied to primes in A171039.
%H A222246 Vincenzo Librandi, <a href="/A222246/b222246.txt">Table of n, a(n) for n = 0..1000</a>
%t A222246 a[n_]:= IntegerDigits[n]/.{5->7, 7->5} // FromDigits; Table[a[n], {n, 0, 80}] (* _Vincenzo Librandi_, Jul 31 2013 *)
%o A222246 (PARI) A222246(n,d=[0, 1, 2, 3, 4, 7, 6, 5, 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 A222246 Cf. A222210-A222254; A171013-A171016, A175770, A171018-A171057.
%K A222246 nonn,base,easy
%O A222246 0,3
%A A222246 _M. F. Hasler_, Feb 13 2013