3,1
G. Kreweras, Les preordres totaux compatibles avec un ordre partiel. Math. Sci. Humaines No. 53 (1976), 5-30.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Sequence in context: A135703 A205669 A101147 * A000347 A089095 A158499
Adjacent sequences: A006325 A006326 A006327 * A006329 A006330 A006331
nonn
N. J. A. Sloane (njas(AT)research.att.com).
