

A334457


Block sizes k of nontrivial biplanes.


1




OFFSET

1,1


COMMENTS

A biplane is an incidence structure consisting of a set P of h points and a set of h blocks, each of which is an ksubset of P (block size k), such that every pair of points lies in exactly 2 blocks (see Alavi et al.).


LINKS

Table of n, a(n) for n=1..7.
Seyed Hassan Alavi, Ashraf Daneshkhah, Cheryl E Praeger, Symmetries of biplanes, arXiv:2004.04535 [math.GR], 2020. See Introduction p. 1.
P. Kaski and P. R. J. Östergård. There are exactly five biplanes with k = 11, J. Combin. Des., 16(2):117127, 2008.


CROSSREFS

Cf. A001109, A003409, A038723, A038725, A054490, A334456 (h).
Sequence in context: A242040 A206822 A195993 * A010456 A072496 A306482
Adjacent sequences: A334454 A334455 A334456 * A334458 A334459 A334460


KEYWORD

nonn,more


AUTHOR

Stefano Spezia, Apr 30 2020


STATUS

approved



