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: A086025 A142764 A123035 this_sequence A156226 A133998 A056217

Adjacent sequences: A006300 A006301 A006302 this_sequence A006304 A006305 A006306

nonn

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