2,5

CRC Handbook of Combinatorial Designs, 1996, p. 480.

Sequence in context: A067866 A157198 A156954 this_sequence A043633 A077723 A078906

Adjacent sequences: A004075 A004076 A004077 this_sequence A004079 A004080 A004081

nonn,hard

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