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%I #4 Jun 02 2016 09:11:16
%S 0,2,1,3,4,5,6,7,11,8,9,101,10,13,103,12,15,17,19,14,21,23,105,16,25,
%T 27,29,31,107,18,33,35,37,39,20,41,43,45,109,22,47,49,51,53,55,57,59,
%U 61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95,97,99,111,113,115,117,119,121,123,125,127,129,131,133,135,137,1001,24,139,141,1003,26,143,145,147,1005,28,149,151,153,155,157,159,161,163,165,167,169,171,173,175,177,179,181,183,185,187,189
%N The successive numbers of digits visible between two even terms are given by the sequence itself.
%C The sequence starts with a(1)=0. It is then extended with the smallest integer not yet present and not leading to a contradiction.
%e The first two even terms that appear in the sequence are 0 and 2; between 0 and 2 there are 0 digits and this 0 corresponds to the starting 0 of the sequence.
%e The next even term is 4 and between 2 and 4 there are 2 digits [which are 1 and 3] and this 2 corresponds to the next term of the sequence.
%e The next even term is 6 and between 4 and 6 there is 1 digit [which is 5] and this 1 corresponds to the next term of the sequence.
%e The next even term is 8 and between 6 and 8 there are 3 digits [which are 7, 1 and 1] and this 3 corresponds to the next term of the sequence.
%e The next even term is 10 and between 8 and 10 there are 4 digits [which are 9, 1, 0 and 1] and this 4 corresponds to the next term of the sequence.
%e Etc.
%K nonn,base
%O 1,2
%A _Eric Angelini_, Jun 01 2016