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 A352720 a(n) is the number of free polyominoes of width 2 and size n. 4
 1, 1, 4, 5, 12, 18, 37, 60, 117, 200, 379, 669, 1250, 2247, 4168, 7570, 13987, 25549, 47108, 86319, 158978, 291806, 537105, 986786, 1815699, 3337560, 6140047, 11289571, 20767180, 38189927, 70246680, 129191148, 237627757, 437042337, 803861244, 1478488577, 2719392160, 5001663330, 9199544069 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,3 LINKS John Mason, Table of n, a(n) for n = 2..1000 John Mason, Java program John Mason, Explanation of formulas R. J. Mathar, Corrigendum to "polyomino enumeration results" (Parkin et al), vixra:1905.0474 (2019) Table 1 column 2. FORMULA For a set of recursive formulas to generate a(n), see the link for the Java program extract. EXAMPLE There is one polyomino, the domino, of width 2 and size 2. So a(2) = 1. There is one tromino, L-shaped, of width 2. So a(3) = 1. CROSSREFS Cf. A000105, A335711, A353067. Sequence in context: A131328 A054451 A309479 * A369697 A308775 A305335 Adjacent sequences: A352717 A352718 A352719 * A352721 A352722 A352723 KEYWORD nonn AUTHOR John Mason, Mar 31 2022 STATUS approved

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Last modified August 5 06:12 EDT 2024. Contains 374935 sequences. (Running on oeis4.)