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A354850
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a(n) is the number of free polyominoes of width 4 and size n.
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2
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1, 3, 21, 59, 198, 703, 2568, 8421, 26165, 78074, 229881, 668082, 1928220, 5523946, 15745682, 44666804, 126251748, 355692380, 999498933, 2802212026, 7841587533, 21907928927, 61123152811, 170333279738, 474197771123, 1319004492132, 3666181193067, 10183729521212
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OFFSET
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4,2
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COMMENTS
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The sequence can be generated using a series of recursive formulas in a fashion similar to A352720 and A353067. These require respectively around 500 and 62000 formula lines, whereas a(n) requires about 10 million lines.
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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