

A103465


Number of polyominoes that can be formed from n regular unit pentagons (or polypents of order n).


13



1, 1, 2, 7, 25, 118, 551, 2812, 14445, 76092, 403976, 2167116, 11698961, 63544050, 346821209, 1901232614
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OFFSET

1,3


COMMENTS

Number of 5polyominoes with n pentagons. A kpolyomino is a nonoverlapping union of n regular unit kgons.
Polypents (or 5polyominoes in Koch and Kurz's terminology) can have holes and this enumeration includes polypents with holes.  George Sicherman, Dec 06 2007


LINKS

Erich Friedman, Math Magic, September and November 2004.


EXAMPLE

a(3)=2 because there are 2 geometrically distinct ways to join 3 regular pentagons edge to edge.


CROSSREFS

Cf. A103465, A103466, A103467, A103468, A103469, A103470, A103471, A103472, A103473, A120102, A120103, A120104.


KEYWORD

more,nonn


AUTHOR

Sascha Kurz, Feb 07 2005; definition revised and sequence extended Apr 12 2006 and again Jun 09 2006


EXTENSIONS



STATUS

approved



