71634

Appears in sequences

• a(n) is the ratio of the sum of the squares of the bends of the spheres that are added in the n-th generation of Apollonian packing of three-dimensional spheres, using "strategy (a)" to count them (see the reference), to the sum of the squares of the bends of the initial five mutually tangent spheres.at n=5A154642
• Free polyominoes with 4n squares, having 90-degree rotational symmetry about a square corner, but not having reflective symmetry.at n=10A234007