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 A374405 #17 Jul 08 2024 02:23:12 %S A374405 0,1,1,2,2,4,3,7,4,6,5,11,6,10,7,8,8,18,9,22,10,15,11,2,12,3,13,35,14, %T A374405 39,15,27,16,13,17,51,18,20,19,59,20,57,21,24,22,4,23,33,24,5,25,81, %U A374405 26,85,27,45,28,93,29,97,30,101,31,34,32,77,33,36,34,108 %N A374405 The nonnegative terms followed by their first position in the concatenation of all terms of the sequence. %C A374405 The nonnegative terms are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, ... They are odd-indexed in the above Data section; the even-indexed terms of the Data section form the last column of the Example section hereunder. %H A374405 Michael S. Branicky, <a href="/A374405/b374405.txt">Table of n, a(n) for n = 1..10000</a> %e A374405 The 1st nonnegative term is 0 and 0 is followed by 1 in the sequence as the earliest 0 of the concatenation of all terms of the sequence is at position 1; %e A374405 the 2nd nonnegative term is 1 and 1 is followed by 2 in the sequence as the earliest 1 of the concatenation of all terms of the sequence is at position 2; %e A374405 the 3rd nonnegative term is 2 and 2 is followed by 4 in the sequence as the earliest 2 of the concatenation of all terms of the sequence is at position 4; %e A374405 the 4th nonnegative term is 3 and 3 is followed by 7 in the sequence as the earliest 3 of the concatenation of all terms of the sequence is at position 7; %e A374405 the 5th nonnegative term is 4 and 4 is followed by 6 in the sequence as the earliest 4 of the concatenation of all terms of the sequence is at position 6; %e A374405 the 6th nonnegative term is 5 and 5 is followed by 11 in the sequence as the earliest 5 of the concatenation of all terms of the sequence is at position 11; %e A374405 the 7th nonnegative term is 6 and 6 is followed by 10 in the sequence as the earliest 6 of the concatenation of all terms of the sequence is at position 10; %e A374405 the 8th nonnegative term is 7 and 7 is followed by 8 in the sequence as the earliest 7 of the concatenation of all terms of the sequence is at position 8; %e A374405 the 9th nonnegative term is 8 and 8 is followed by 18 in the sequence as the earliest 8 of the concatenation of all terms of the sequence is at position 18; %e A374405 the 10th nonnegative term is 9 and 9 is followed by 22 in the sequence as the earliest 9 of the concatenation of all terms of the sequence is at position 22; %e A374405 the 11th nonnegative term is 10 and 10 is followed by 15 in the sequence as the earliest 10 of the concatenation of all terms of the sequence is at position 15; %e A374405 the 12th nonnegative term is 11 and 11 is followed by 2 in the sequence as the earliest 11 of the concatenation of all terms of the sequence is at position 2; %e A374405 the 13th nonnegative term is 12 and 12 is followed by 3 in the sequence as the earliest 12 of the concatenation of all terms of the sequence is at position 3; etc. %o A374405 (Python) %o A374405 from itertools import count, islice %o A374405 def agen(): # generator of terms %o A374405 s = "" %o A374405 for n in count(0): %o A374405 sn = str(n) %o A374405 s += sn %o A374405 locn = 1 + s.index(sn) %o A374405 s += str(locn) %o A374405 yield from [n, locn] %o A374405 print(list(islice(agen(), 70))) # _Michael S. Branicky_, Jul 07 2024 %Y A374405 Cf. A001477, A097614. %K A374405 base,nonn %O A374405 1,4 %A A374405 _Eric Angelini_, Jul 07 2024 %E A374405 a(63) and beyond from _Michael S. Branicky_, Jul 07 2024