220150

Appears in sequences

• Number of nonempty subsets of {1,2,...,n} in which exactly 2/5 of the elements are <= (n-3)/3.at n=22A048033
• a(n)=If[IntegerQ[((3*n - 2)/( n + 1))*a(n - 1)], ((3*n - 2)/(n + 1))* a(n - 1), If[IntegerQ[((4*n - 2)/(n + 1))*a( n - 1)], ((4*n - 2)/(n + 1))*a(n - 1), n*a(n - 1)]].at n=13A155580
• Number of distinct intersections among all circles that can be constructed on vertices of an n-sided regular polygon, using only a compass.at n=34A331702