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A054963
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Number of cells in the first column of all directed column-convex polyominoes of area n+1.
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1
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1, 3, 9, 26, 72, 194, 515, 1357, 3563, 9340, 24466, 64068, 167749, 439191, 1149837, 3010334, 7881180, 20633222, 54018503, 141422305, 370248431, 969323008, 2537720614, 6643838856, 17393795977, 45537549099, 119218851345
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| E. Barcucci, R. Pinzani and R. Sprugnoli, Directed column-convex polyominoes by recurrence relations, Lecture Notes in Computer Science, No. 668, Springer, Berlin, 1993, pp. 282-298.
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FORMULA
| a_n = fibonacci(2n)+fibonacci(2n+2)-n; generating function = (1-2x+2x^2)/((1-x)^2(1-3x+x^2))
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CROSSREFS
| Sequence in context: A138237 A121286 A072863 * A118046 A057153 A084787
Adjacent sequences: A054960 A054961 A054962 * A054964 A054965 A054966
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KEYWORD
| nonn
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AUTHOR
| Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 16 2001
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