login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A001201 Steiner triple systems (STS's) on 6n+1 or 6n+3 elements.
(Formerly M5214 N2268)
8
1, 1, 30, 840, 1197504000, 60281712691200, 1348410350618155344199680000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

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

REFERENCES

L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 304.

CRC Handbook of Combinatorial Designs, 1996, p. 70.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=0..6.

P. Kaski and P. R. J. Östergård, The Steiner triple systems of order 19, Math. Comp. 73 (2004), 2075-2092.

Index entries for sequences related to Steiner systems

EXAMPLE

There are 1197504000 STS's on 13 elements.

CROSSREFS

Indexed by A047241. Cf. A030128, A030129, A051390.

Sequence in context: A049394 A143169 A256324 * A007850 A162833 A163208

Adjacent sequences:  A001198 A001199 A001200 * A001202 A001203 A001204

KEYWORD

nonn,nice,hard,more

AUTHOR

N. J. A. Sloane

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 10 04:09 EST 2016. Contains 278993 sequences.