3,2
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: A017978 A163610 A055825 * A058120 A000349 A036919
Adjacent sequences: A006323 A006324 A006325 * A006327 A006328 A006329
nonn
N. J. A. Sloane (njas(AT)research.att.com).
