A051391 Number of nonisomorphic Steiner triple systems (STS's) S(2,3,v) on v = 6n+1 or 6n+3 points.

1, 1, 1, 1, 2, 80, 11084874829

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.

Petteri Kaski and Patric R. J. Östergård, The Steiner triple systems of order 19

Petteri Kaski and Patric R. J. Östergård, The Steiner triple systems of order 19, Mathematics of Computation, Vol. 73, No. 248 (Oct., 2004), pp. 2075-2092.

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: A369468 A293290 A056972 * A041799 A187858 A371508

Adjacent sequences: A051388 A051389 A051390 * A051392 A051393 A051394

Keyword

nonn,nice,hard

Author

N. J. A. Sloane

Status

approved