A030128 Number of Steiner triple systems (STS's) on n elements.

1, 0, 1, 0, 0, 0, 30, 0, 840, 0, 0, 0, 1197504000, 0, 60281712691200, 0, 0, 0, 1348410350618155344199680000

Offset

1,7

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..19.

Yue Guan, Minjia Shi, and Denis S. Krotov, The Steiner triple systems of order 21 with a transversal subdesign TD(3,6), arXiv:1905.09081 [math.CO], 2019.

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

Minjia Shi, Li Xu, and Denis S. Krotov, The number of the non-full-rank Steiner triple systems, arXiv:1806.00009 [math.CO], 2018.

Index entries for sequences related to Steiner systems

Crossrefs

Cf. A001201, A030129, A051390.

Sequence in context: A277043 A361058 A198805 * A137348 A137737 A262706

Adjacent sequences: A030125 A030126 A030127 * A030129 A030130 A030131

Keyword

nonn,nice,hard,more

Author

N. J. A. Sloane

Status

approved