A378169 Number of free polyominoes with n cells with at most 3 collinear cell centers on any line in the plane.

1, 1, 2, 4, 9, 18, 37, 62, 86, 78, 61, 34, 14, 4, 1

Offset: 1

Author

Dave Budd, Nov 18 2024

Keywords

• nonn
• fini
• full

Examples

			For n=15, the only polyomino is
    ###
  ###
###
  ## #
   ###
		

Links

• Dave Budd, Exhaustive proof of A378169

Crossrefs

Cf. A000105, A377756, A377942.

Programs

Python

# See link

Formula

a(n) = Sum_{k=1..3} A377942(n,k).