A135942 Number of n-celled polyominoes with perimeter < 2n+2.

0, 0, 0, 1, 1, 8, 25, 114, 438, 1826, 7339, 29876, 120346, 485155, 1947974, 7812084, 31267765

Offset

1,6

Comments

These are n-cell polyominoes with the perimeter less than the maximum possible one.

If we associate a graph to a polyomino with vertices representing cells and edges representing two cells with a common edge, then this sequence enumerates polyominoes whose corresponding graphs have cycles.

Links

Table of n, a(n) for n=1..17.

Formula

a(n) = A000105(n) - A131482(n).

Crossrefs

Sequence in context: A229443 A335769 A139026 * A181207 A068315 A069586

Adjacent sequences: A135939 A135940 A135941 * A135943 A135944 A135945

Keyword

hard,more,nonn

Author

Tanya Khovanova, Mar 03 2008

Extensions

More terms from Joerg Arndt, May 21 2018

Status

approved