%I A001201 M5214 N2268
%S A001201 1,1,30,840,1197504000,60281712691200,1348410350618155344199680000
%N A001201 Steiner triple systems (STS's) on 6n+1 or 6n+3 elements.
%D A001201 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A001201 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A001201 L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 304.
%D A001201 CRC Handbook of Combinatorial Designs, 1996, p. 70.
%H A001201 P. Kaski and P. R. J. \"Osterg{\aa}rd (Patric.Ostergard(AT)hut.fi), <a 
               href="http://www.tcs.hut.fi/~pkaski/sts19.ps">The Steiner triple 
               systems of order 19</a>
%H A001201 <a href="Sindx_St.html#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.
%Y A001201 Sequence in context: A160269 A049394 A143169 this_sequence A007850 A158580 
               A097313
%Y A001201 Adjacent sequences: A001198 A001199 A001200 this_sequence A001202 A001203 
               A001204
%K A001201 nonn,nice,hard
%O A001201 0,3
%A A001201 N. J. A. Sloane (njas(AT)research.att.com).