438273

Appears in sequences

• Let P(A) be the power set of an n-element set A. Then a(n) = the number of pairs of elements {x,y} of P(A) for which either 0) x and y are disjoint and for which either x is a subset of y or y is a subset of x, or 1) x and y are intersecting but for which x is not a subset of y and y is not a subset of x.at n=10A134018
• G.f. satisfies A(x) = (1 + x) * (1 + x*A(x)^6).at n=6A364339