Let P(A) denote 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 x is not a subset of y and y is not a subset of x, 1) x and y are disjoint and for which either x is a subset of y or y is a subset of x, or 2) x and y intersect but for which x is not a subset of y and y is not a subset of x.
A133789
Let P(A) denote 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 x is not a subset of y and y is not a subset of x, 1) x and y are disjoint and for which either x is a subset of y or y is a subset of x, or 2) x and y intersect but for which x is not a subset of y and y is not a subset of x.
Terms
- a(0) =0a(1) =1a(2) =4a(3) =16a(4) =70a(5) =316a(6) =1414a(7) =6196a(8) =26590a(9) =112156a(10) =466774a(11) =1923076a(12) =7863310a(13) =31972396a(14) =129459334a(15) =522571156a(16) =2104535230a(17) =8460991036a(18) =33972711094a(19) =136277478436a(20) =546270602350
External references
- oeis: A133789