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Search: id:A000303
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| A000303 |
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Number of permutations of [n] in which the longest run has length 2.
(Formerly M3522 N1430)
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+0
2
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| 1, 4, 16, 69, 348, 2016, 13357, 99376, 822040, 7477161, 74207208, 797771520, 9236662345, 114579019468, 1516103040832, 21314681315997
(list; graph; listen)
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OFFSET
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2,2
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REFERENCES
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F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied Tables, Cambridge, 1966, p. 261, Table 7.4.1.
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EXAMPLE
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a(3)=4 because we have (13)2, 2(13), (23)1, 3(12), where the parentheses surround runs of length 2.
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CROSSREFS
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Column 2 of A008304.
Sequence in context: A128730 A006319 A059606 this_sequence A133789 A091354 A124533
Adjacent sequences: A000300 A000301 A000302 this_sequence A000304 A000305 A000306
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KEYWORD
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nonn
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AUTHOR
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njas
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EXTENSIONS
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Better description from Emeric Deutsch (deutsch(AT)duke.poly.edu), May 08 2004
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