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 A105310 #6 Feb 16 2025 08:32:57 %S A105310 1,1122,111222333,1111222233334444,1111122222333334444455555, %T A105310 111111222222333333444444555555666666, %U A105310 1111111222222233333334444444555555566666667777777 %N A105310 a(n) = concatenation of i n times, with i = 1 to n. %D A105310 F. Smarandache, "Properties of the numbers", Univ. of Craiova Archives, 1975; Arizona State University Special Collections, Tempe, AZ. %H A105310 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SmarandacheSequences.html">Smarandache Sequences</a>. %e A105310 a(10)=concatenation of (1^10)(2^10)(3^10)...(9^10)(10^10) %Y A105310 Cf. A098129, A000461. %K A105310 base,easy,nonn,less %O A105310 21,2 %A A105310 _Alexandre Wajnberg_, Apr 25 2005