1,5
Tomas Oliveira e Silva, Enumeration of polyominoes
Cf. A000105, A006746.
Sequence in context: A048083 A127931 A077237 * A006746 A205875 A121624
Adjacent sequences: A056876 A056877 A056878 * A056880 A056881 A056882
nonn
N. J. A. Sloane (njas(AT)research.att.com), Sep 03 2000