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 A122981 Number of distributive sublattices of the lattice of k-tuples less than the n-th partition (in Abramowitz and Stegun order). 3
 3, 7, 12, 15, 37, 73, 31, 103, 146, 319, 731, 63, 271, 505, 1191, 1833, 4618 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS After a(18) - for partition [1^5] - the sequence continues ?, 127, 687, 1611, 2102, 4031, 8589, ?, ?, ?, ?, ?, 255. LINKS M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy]. EXAMPLE For a(5), partition [2,1], the lattice consists of the 6 pairs (i,j) where 0<=i<=2 and 0<=j<=1, with (i,j) <= (i',j') iff i<=i' and j<=j'. {(2,1), (2,0), (0,1), (0,0)} is one distributive sublattice. CROSSREFS Cf. A122978, A122982, A122979, A036036, A074139. Sequence in context: A096998 A317307 A331042 * A122982 A101589 A061559 Adjacent sequences:  A122978 A122979 A122980 * A122982 A122983 A122984 KEYWORD more,nonn AUTHOR Franklin T. Adams-Watters, Sep 21 2006 STATUS approved

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Last modified April 19 20:11 EDT 2021. Contains 343117 sequences. (Running on oeis4.)