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 A001201 M5214 N2268 #28 Jun 17 2022 03:23:17 %S A001201 1,1,30,840,1197504000,60281712691200,1348410350618155344199680000 %N A001201 Number of Steiner triple systems (STS's) on 6n+1 or 6n+3 elements. %C A001201 To be precise, for n even, a(n) is the number of STS's on 3n+1 elements, and for n odd, a(n) is the number of STS's on 3n elements. - _Franklin T. Adams-Watters_, Apr 10 2010 %D A001201 L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 304. %D A001201 CRC Handbook of Combinatorial Designs, 1996, p. 70. %D A001201 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). %D A001201 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A001201 Petteri Kaski and Patric R. J. Östergård, <a href="http://dx.doi.org/10.1090/S0025-5718-04-01626-6">The Steiner triple systems of order 19</a>, Math. Comp. 73 (2004), 2075-2092. %H A001201 <a href="/index/St#Steiner">Index entries for sequences related to Steiner systems</a> %e A001201 There are 1197504000 STS's on 13 elements. %Y A001201 Indexed by A047241. Cf. A030128, A030129, A051390. %K A001201 nonn,nice,hard,more %O A001201 0,3 %A A001201 _N. J. A. Sloane_