6,1

CRC Handbook of Combinatorial Designs, 1996, p. 285.

Sequence in context: A004568 A079904 A021420 this_sequence A054003 A134352 A152648

Adjacent sequences: A011991 A011992 A011993 this_sequence A011995 A011996 A011997

nonn,hard

N. J. A. Sloane (njas(AT)research.att.com).