2,3

L. Travis, [math/9811127] Graphical Enumeration: A Species-Theoretic Approach

Cf. A001373.

Sequence in context: A093033 A156929 A123796 this_sequence A131237 A024082 A132547

Adjacent sequences: A129521 A129522 A129523 this_sequence A129525 A129526 A129527

nonn

Vladeta Jovovic (vladeta(AT)eunet.rs), May 29 2007