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A131482 a(n) is the number of n-celled 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 n-celled polyomino. a(n) is the number of n-celled 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

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Last modified October 19 09:28 EDT 2018. Contains 316339 sequences. (Running on oeis4.)