1,1

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.

Table of n, a(n) for n=1..10.

a(2) = 6 because the 6 elements of rank 2 are x + y, x + z, y + z, xy, xz and yz.

Sequence in context: A179652 A253855 A298860 * A101060 A278486 A038064

Adjacent sequences: A068976 A068977 A068978 * A068980 A068981 A068982

more,nonn

David Wasserman, Mar 31 2002

approved