OFFSET
1,1
COMMENTS
The rank of a lattice term is the number of occurrences of variables in that term. The rank of an element is the minimum rank of a term representing that element.
EXAMPLE
a(2) = 6 because the 6 elements of rank 2 are x + y, x + z, y + z, xy, xz and yz.
CROSSREFS
KEYWORD
more,nonn
AUTHOR
David Wasserman, Mar 31 2002
STATUS
approved