[seqfan] Smeared polyominoes

Allan Wechsler acwacw at gmail.com
Sun Sep 16 03:21:46 CEST 2018

The number of polyominoes of order n which possess an axis along which
every cell has a neighbor. The straight tromino works, for example, but the
L-tromino does not, because along both the X and Y axes, there is one cell
with no neighbors on either side

My hand calculation, for n ranging from 1 to 7: 0,1,1,3,3,9,16; this is
already not in OEIS.

I'm not creating an entry in OEIS yet, because these are just hand-counted
(from looking at exhaustive sets of polyominoes at Wikipedia). Can somebody
who has decent polyomino-handling software verify these values, and maybe
give a few more? I'm going cross-eyed already.

More information about the SeqFan mailing list