OFFSET
4,3
COMMENTS
Note that for k=4 (polyominoes with square bounding rectangle) these are not the free polyominoes, because Read does not apply the full symmetry group of order 8 to reduce the fixed polyominoes for d_q(n), but only the symmetry group of order 4 (excluding the 90 deg rotations). The free polyominoes with square bounding rectangles are his z_4(n) instead. - R. J. Mathar, May 12 2019
LINKS
R. C. Read, Contributions to the cell growth problem, Canad. J. Math., 14 (1962), 1-20.
EXAMPLE
Triangle starts:
1;
0,3;
0,6,15;
0,2,39, 30;
0,1,59,148, 61;
0,0,42,349, 383, 97;
0,0,21,519,1304, 822, 155;
0,0, 4,488,2847, 3548, 1551, 220;
0,0, 1,321,4441,10323, 8239, 2680, 313;
0,0, 0,122,5008,21995,29442,16821, 4327,415;
0,0, 0, 35,4168,36035,79155,71742,31576,...
There are T(5,2)=3 out of 12 pentominoes that fill the 4X2 shape: the L, N and Y. The F, T, V, W, X, and Z require both dimensions >= 3; the P and U would fit but not touch all sides; the I requires one dimension of 5. - R. J. Mathar, May 08 2019
CROSSREFS
KEYWORD
AUTHOR
N. J. A. Sloane, Feb 05 2001
EXTENSIONS
Changed 518 to 519 (correcting Read...) and added values for n>=11 cells. R. J. Mathar, May 12 2019
STATUS
approved