A122981 Number of distributive sublattices of the lattice of k-tuples less than the n-th partition (in Abramowitz and Stegun order).

3, 7, 12, 15, 37, 73, 31, 103, 146, 319, 731, 63, 271, 505, 1191, 1833, 4618

Offset

1,1

Comments

After a(18) - for partition [1^5] - the sequence continues ?, 127, 687, 1611, 2102, 4031, 8589, ?, ?, ?, ?, ?, 255.

Links

Table of n, a(n) for n=1..17.

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: A356353 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