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 A100748 #7 Dec 12 2013 15:50:48 %S A100748 -240,-164,-86,-11,66,141,218,295,374,451,530,607,684,760,837,912,989, %T A100748 1066,1145,1222,1301,1378,1456,1531,1607,1682,1759,1835,1910,1985 %N A100748 Years of recorded appearances of Halley's Comet (negative years are B.C.). %C A100748 This sequence is not well-defined for many reasons (negative years are ill-defined; calendars change often, so when does a year begin?; what does "observed" mean?; what if the comet was observed both at the end of one year and at the beginning of another, as in 1985/1986?; etc.). - _N. J. A. Sloane_, Jun 24 2007 %H A100748 Joseph M. Laufer, <a href="http://www.lauferworld.com/haleyhome.html">Halley's Comet, Its 30th Recorded Return, 1985-1986</a>. %e A100748 a(30) = 1985 because the 30th recorded appearance of Halley's comet was in 1985. %Y A100748 See A072235 for another version. %K A100748 sign %O A100748 1,1 %A A100748 _David Terr_, Jan 03 2005