Consider a (solid) triangle with n cells on each edge, for a total of n(n+1)/2 cells; a(n) is number of inequivalent ways of labeling cells with 0's and 1's; triangle may be rotated and turned over.

A061348

Consider a (solid) triangle with n cells on each edge, for a total of n(n+1)/2 cells; a(n) is number of inequivalent ways of labeling cells with 0's and 1's; triangle may be rotated and turned over.