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 A222211 #17 Apr 06 2019 17:48:40
%S A222211 2,1,0,3,4,5,6,7,8,9,12,11,10,13,14,15,16,17,18,19,2,1,0,3,4,5,6,7,8,
%T A222211 9,32,31,30,33,34,35,36,37,38,39,42,41,40,43,44,45,46,47,48,49,52,51,
%U A222211 50,53,54,55,56,57,58,59,62,61,60,63,64,65,66,67,68,69,72,71,70,73,74,75
%N A222211 In the number n, replace all (decimal) digits '0' with '2' and vice versa.
%C A222211 The map which is applied to primes in A171014.
%C A222211 Programs should omit leading '0' digits in the resulting terms. - _Georg Fischer_, Apr 06 2019
%H A222211 Vincenzo Librandi, <a href="/A222211/b222211.txt">Table of n, a(n) for n = 0..1000</a>
%t A222211 a[n_]:= IntegerDigits[n]/.{0->2, 2->0} // FromDigits; Table[a[n], {n, 0, 80}] (* _Vincenzo Librandi_, Jul 29 2013 *)
%o A222211 (PARI) A222211(n,d=[2,1,0,3,4,5,6,7,8,9])={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)
%o A222211 (Perl) print join(",", map{tr/02/20/; $_+0}(0..75)); # _Georg Fischer_, Apr 06 2019
%Y A222211 Cf. A222210-A222254 (other digit pairs), A171013-A171057, A175770 (in prime numbers).
%K A222211 nonn,base,easy
%O A222211 0,1
%A A222211 _M. F. Hasler_, Feb 12 2013