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 A309590 #12 Apr 10 2019 10:48:12
%S A309590 0,1,2,3,4,5,6,7,8,9,0,1,12,23,34,45,56,67,78,89,2,3,4,5,6,7,8,9,10,
%T A309590 11,13,14,15,16,17,18,19,20,21,22,24,25,26,27,28,29,30,31,32,33,35,36,
%U A309590 37,38,39,40,41,42,43,44,46,47,48,49,50,51,52,53,54,55
%N A309590 Inverse of A309589: 0-based positions in the number subsets {0, ..., 10^k - 1} written in base 10 and sorted lexicographically, for k = 1, 2, ...
%C A309590 The sequence is related to the flattened form of the irregular table T(k, i) described in A309589. There, the rows for k >= 1 contain a permutation of the numbers 0 <= i <= 10^k - 1 which is defined by the lexicographical order of the numbers i written in base 10.
%C A309590 The sequence here lists, per sorted row k, the 0-based positions of the numbers i in that row. The positions in row k are also a permutation of the numbers 0 <= i <= 10^k - 1.
%H A309590 Georg Fischer, <a href="/A309589/a309589.txt">Perl program</a> which generates A309589 and this sequence.
%o A309590 (Perl) # cf. link
%Y A309590 Cf. A119590 (like row k=2, but i = 1..100), A190017 (like row k=4, but for i = 1..10000), A309589.
%K A309590 nonn,base,easy,tabf
%O A309590 0,3
%A A309590 _Georg Fischer_, Mar 02 2019