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%I #17 Feb 14 2021 13:18:15
%S 0,1,2,3,4,5,6,7,8,9,10,11,13,2,14,15,16,17,18,19,20,15,22,33,24,25,
%T 26,27,28,29,30,31,17,20,54,35,36,37,38,39,40,53,35,17,44,75,46,5,48,
%U 49,50,16,52,23,13,55,95,57,58,7,60,87,69,51,64,26,66,115,68,15,70,106,79,71,61,36
%N a(n) is the number of digits from the end of the concatenation of all previous terms where n last appears. If n has not previously appeared then a(n) = n.
%H Scott R. Shannon, <a href="/A341537/a341537.png">Image of the terms for n=0..500000</a>.
%e a(9) = 9 as the concatenation of all previous terms is "012345678" which does not include 9, so a(9) = 9.
%e a(12) = 13 as the concatenation of all previous terms is "01234567891011" which includes "12" as a substring, starting 13 digits from the end of the concatenation.
%e a(13) = 2 as the concatenation of all previous terms is "0123456789101113" which includes "13" as a substring, starting 2 digits from the end of the concatenation.
%Y Cf. A333921, A337227, A007908, A116700, A131881.
%K nonn,base
%O 0,3
%A _Scott R. Shannon_, Feb 14 2021
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