1,9
A. Betten, G. Brinkmann and T. Pisanski, Counting symmetric configurations v_3, Discrete Appl. Math., 99 (2000), 331-338.
Cf. A001403, A023994.
Sequence in context: A022693 A174498 A146478 * A191320 A180228 A197376
Adjacent sequences: A098801 A098802 A098803 * A098805 A098806 A098807
nonn,hard
N. J. A. Sloane (njas(AT)research.att.com), Nov 05 2004