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 A123456 #34 Aug 07 2021 01:11:45 %S A123456 -20,56,55,56,55,56,51,54,52,49,32,37,40,44,49,51,32,36,44,48,51,52, %T A123456 32,37,44,56,55,56,55,56,51,54,52,49,32,37,40,44,49,51,32,36,44,52,51, %U A123456 49,32,37,-20,56,55,56,55,56,51,54,52,49,32,37,40,44,49,51,32,36,44,48,51,52,32,37 %N A123456 Ludwig van Beethoven, Bagatelle No. 25, "Für Elise". %C A123456 From the source file for a MIDI player. This is intended to demonstrate the "Listen to a sequence" capability of the OEIS. %H A123456 N. J. A. Sloane, <a href="/A123456/b123456.txt">Table of n, a(n) for n = 1..761</a> %H A123456 Everything2.com, <a href="/A123456/a123456.txt">List of notes in MIDI format together with tempo indications</a> [from the link below] %H A123456 Everything2.com, <a href="http://everything2.com/index.pl?node_id=770282">Für Elise</a> %H A123456 N. J. A. Sloane, <a href="/play.html">Listening to a sequence</a> %H A123456 <a href="/index/Mu#music">Index entries for sequences related to music</a> %Y A123456 Cf. A144488. %K A123456 sign,hear,fini,full %O A123456 1,1 %A A123456 _N. J. A. Sloane_ and _Nadia Heninger_, Jun 19 2006 %E A123456 At _David Applegate_'s suggestion, 20 has been subtracted from each entry to make this sound better with the default settings used by the OEIS MIDI player. See A144488 for the old version.