2,2
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
T. R. S. Walsh and A. B. Lehman, Counting rooted maps by genus, J. Comb. Thy B13 (1972), 122-141 and 192-218.
Sequence in context: A197240 A142764 A123035 * A156226 A133998 A056217
Adjacent sequences: A006300 A006301 A006302 * A006304 A006305 A006306
nonn
N. J. A. Sloane (njas(AT)research.att.com).
