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A051391 Number of nonisomorphic Steiner triple systems (STS's) S(2,3,v) on v = 6n+1 or 6n+3 points. 0
1, 1, 1, 1, 2, 80, 11084874829 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

REFERENCES

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

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

LINKS

Table of n, a(n) for n=1..7.

P. Kaski and P. R. J. Ostergard (Patric.Ostergard(AT)hut.fi), The Steiner triple systems of order 19

Index entries for sequences related to Steiner systems

EXAMPLE

There are 2 nonisomorphic STS's on 13 points.

CROSSREFS

Indexed by A047241. Cf. A001201, A030128, A030129, A051390, A124118, A124119.

Sequence in context: A291331 A293290 A056972 * A041799 A187858 A072408

Adjacent sequences:  A051388 A051389 A051390 * A051392 A051393 A051394

KEYWORD

nonn,nice,hard

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified November 18 17:49 EST 2018. Contains 317323 sequences. (Running on oeis4.)