

A131482


a(n) is the number of ncelled polyominoes with perimeter 2n+2.


6



1, 1, 2, 4, 11, 27, 83, 255, 847, 2829, 9734, 33724, 118245, 416816, 1478602, 5267171, 18840144
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,3


COMMENTS

2n+2 is the maximal perimeter of an ncelled polyomino. a(n) is the number of ncelled polyominoes that have a tree as their connectedness graph (vertices of this graph correspond to cells and two vertices are connected if the corresponding cells have a common edge)


LINKS

Table of n, a(n) for n=1..17.
Andrew Clarke, Isoperimetrical Polyominoes, The Poly Pages.


CROSSREFS

a(n) <= A000105(n), a(n) <= A057730(n+1).
Sequence in context: A316696 A319616 A148130 * A234845 A148131 A234844
Adjacent sequences: A131479 A131480 A131481 * A131483 A131484 A131485


KEYWORD

hard,more,nonn


AUTHOR

Tanya Khovanova, Jul 27 2007


EXTENSIONS

a(14)a(16) from David Radcliffe, Dec 25 2017
a(17) from David Radcliffe, Dec 26 2017


STATUS

approved



