A367557 The number of fixed kissing polyominoes with n cells.

4, 40, 260, 1428, 7184, 34238, 157398, 705518, 3104394, 13469766, 57811669, 245990766

Offset: 7

Author

Johann Peters, Nov 22 2023

Keywords

• nonn
• hard
• more

Comments

Translations are allowed, but not rotations or reflections.

A polyomino is 'kissing' if there exist two cells that touch only at a corner such that no cell exists touching both edgewise simultaneously.

First thirteen terms calculated by filtering the output of Redelmeier's Algorithm.

Examples

			The smallest kissing polyomino has area 7; its four rotations determine the first term in the sequence:
    OOO
    O O
    OO
		

Links

• Alain Goupil, Marie-Eve Pellerin, and Jérôme de Wouters d'Oplinter, Partially Directed Snake Polyominoes, Discrete Applied Mathematics, Volume 236, 2018.

Crossrefs

Cf. A182644, A376496.

Extensions

a(14)-a(18) from John Mason, Sep 25 2024