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 A299972 #6 Feb 23 2018 09:46:49
%S A299972 1,11,9,3,17,4,8,12,10,2,18,5,7,13,14,6,15,27,25,37,35,47,45,57,55,65,
%T A299972 56,16,26,36,46,66,54,28,24,38,34,48,44,58,62,20,22,30,32,40,42,50,52,
%U A299972 60,61,21,31,41,51,69,23,19,33,29,43,39,53,49,63,59,64,68
%N A299972 Lexicographic first sequence of positive integers such that a(n) + a(n+1) has a digit 2, and no term occurs twice.
%C A299972 A permutation of the positive integers.
%o A299972 (PARI) a(n,f=1,d=2,a=1,u=[a])={for(n=2,n,f&&if(f==1,print1(a","),write(f,n-1," "a));for(k=u[1]+1,oo,setsearch(u,k)&&next;setsearch(Set(digits(a+k)),d)&&(a=k)&&break);u=setunion(u,[a]);u[2]==u[1]+1&&u=u[^1]);a}
%Y A299972 Cf. A299970 (analog with digit 0), A299957 (digit 1), A299973..A299979 (digit 3..9).
%K A299972 nonn,base
%O A299972 1,2
%A A299972 _M. F. Hasler_ and _Eric Angelini_, Feb 22 2018