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 disjoint and for which x is not a subset of y and y is not a subset of x, or 2) x and y are intersecting but for which x is not a subset of y and y is not a subset of x, or 3) x = y.
A134165
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 disjoint and for which x is not a subset of y and y is not a subset of x, or 2) x and y are intersecting but for which x is not a subset of y and y is not a subset of x, or 3) x = y.
Terms
- a(0) =1a(1) =3a(2) =8a(3) =24a(4) =86a(5) =348a(6) =1478a(7) =6324a(8) =26846a(9) =112668a(10) =467798a(11) =1925124a(12) =7867406a(13) =31980588a(14) =129475718a(15) =522603924a(16) =2104600766a(17) =8461122108a(18) =33972973238a(19) =136278002724a(20) =546271650926
External references
- oeis: A134165