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 A019524 #14 Feb 16 2025 08:32:33 %S A019524 11,1212,123123,12341234,1234512345,123456123456,12345671234567, %T A019524 1234567812345678,123456789123456789,1234567891012345678910, %U A019524 12345678910111234567891011,123456789101112123456789101112 %N A019524 Duplicate terms of A007908. %D A019524 F. Iacobescu, Smarandache Partition Type and Other Sequences, Bull. Pure Appl. Sciences, Vol. 16E, No. 2 (1997), pp. 237-240. %H A019524 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SmarandacheSequences.html">Smarandache Sequences</a> %H A019524 F. Smarandache, <a href="http://www.gallup.unm.edu/~smarandache/CP2.pdf">Collected Papers, Vol. II</a> %H A019524 F. Smarandache, <a href="http://www.gallup.unm.edu/~smarandache/Sequences-book.pdf">Sequences of Numbers Involved in Unsolved Problems</a>. %F A019524 a(n) = A007908(n)*(1 + 10^A058183(n)) = (n + a(n - 1)*10^L(n)/(1 + 10^(n*L(n - 1) - (10^L(n - 1) - 1)/9)))*(1 + 10^((n + 1)*L(n) - (10^L(n) - 1)/9)) where L(n) = floor(log_10(10n)). - _Henry Bottomley_, Nov 17 2000 (may need to be adapted for change in offset) %K A019524 nonn %O A019524 1,1 %A A019524 R. Muller