A362708 a(n) is the number of almost unitary polyominoes of size n. An almost unitary polyomino is one in which all but 1 of its perimeter walls have length 1.
0, 0, 0, 1, 0, 0, 2, 2, 1, 6, 9, 11, 21, 49, 69, 117, 249, 427
Offset: 1
Examples
a(4)=1 because of: O OO O
Links
- George Sicherman, Catalogue of Almost Unitary Polyominoes