A057973 Number of polybricks: number of ways to arrange n 1 X 2 "bricks" in a wall (see illustrations).

1, 2, 5, 16, 55, 225, 949, 4269, 19500, 91115, 429742, 2047660, 9820197, 47383255, 229725560, 1118568692, 5466616025, 26804560282, 131817042605, 649952289243

Offset: 1

Author

Warren Power (wjpnply(AT)hotmail.com), Oct 21 2000

Keywords

• nonn
• nice

Comments

The tiling of bricks is topologically the same as that by regular hexagons and this sequence can also be seen as counting polyhexes where two polyhexes are equivalent iff they are related by a symmetry that is also a symmetry of the tiling by bricks.

References

• Other references on polyforms are: www.mathpuzzle.com, Solomon W. Golomb, Ed Pegg, Eric Weisstein, David A. Klarner (Packing rectangles) and Michael Reid [These references should be expanded! - N. J. A. Sloane]

Links

• Brendan Owen and Livio Zucca, Polyform generation
• Brendan Owen and Livio Zucca, The 16 polybricks of order 4
• N. J. A. Sloane, The polybricks of orders 1, 2 and 3

Extensions

More terms from Don Reble, Nov 01 2001

Corrected and extended by Joseph Myers, Sep 21 2002