OFFSET
1,5
COMMENTS
Number of free polyominoes that can be made from the polyomino with binary code A246521(n+1) by moving one of its cells (not counting itself), where the intermediate (the set of cells remaining when the cell to be moved is detached) is required to be a (connected) polyomino.
Can be read as an irregular triangle, whose m-th row contains A000105(m) terms, m >= 1.
LINKS
Pontus von Brömssen, Table of n, a(n) for n = 1..6473 (rows 1..10).
FORMULA
a(n) <= A367126(n).
EXAMPLE
As an irregular triangle:
0;
0;
1, 1;
4, 3, 4, 3, 2;
10, 8, 3, 9, 10, 9, 8, 9, 10, 8, 4, 2;
...
For n = 8, A246521(8+1) = 30 is the binary code of the S-tetromino. By moving one cell of the S-tetromino, we can obtain the L, O, and T tetrominoes (but not the I tetromino), so a(8) = 3.
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Pontus von Brömssen, Nov 18 2023
STATUS
approved