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A268371 Triangle read by rows: T(n,k) is the number of free polyominoes with width n and height 1<=k<=n. 6
1, 1, 2, 1, 6, 24, 1, 12, 181, 1051, 1, 30, 941, 21992, 238048, 1, 65, 4662, 228013, 9735647, 195284973, 1, 158, 23691, 2337694, 195616247, 15256715219, 577169894573 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Superset of Craig Knecht's A268311.
LINKS
R. Parkin, L. J. Lander, and D. R. Parkin, Polyomino Enumeration Results, presented at SIAM Fall Meeting, 1967, and accompanying letter from T. J. Lander (annotated scanned copy) page 9 (incorrect at n=15).
EXAMPLE
The first rows of the array are:
1;
1, 2;
1, 6, 24;
1, 12, 181, 1051;
...
T(4,3)=181 = 15+39+59+42+21+4+1: In the 4x3 square fit 15 6-ominoes, 39 7-ominoes, 59 8-ominoes, 42 9-ominoes, 21 10-ominoes, 4 11-ominoes or 1 12-omino. - R. J. Mathar, Jun 07 2020
CROSSREFS
Cf. A268311 (right diagonal), A335711 (column n=2), A000105 (free polyominoes), A292357 (equival. for fixed polys).
Sequence in context: A025271 A153804 A239740 * A318918 A100404 A355005
KEYWORD
nonn,tabl,more,changed
AUTHOR
John Mason, Feb 03 2016
EXTENSIONS
a(16)-a(28) from Jean-Luc Manguin, May 25 2020
STATUS
approved

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Last modified March 28 11:59 EDT 2024. Contains 371254 sequences. (Running on oeis4.)