4,2

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

R. E. Peile, Some Topics in Combinatorial Theory. Ph. D. Dissertation, Oxford University, 1979.

Sequence in context: A115587 A018337 A092389 this_sequence A121234 A084574 A087621

Adjacent sequences: A005271 A005272 A005273 this_sequence A005275 A005276 A005277

nonn

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