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Search: id:A000402
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| A000402 |
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Number of permutations of [n] in which the longest run has length 3.
(Formerly M4239 N1771)
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+0
2
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| 1, 6, 41, 293, 2309, 19975, 189524, 1960041, 21993884, 266361634, 3465832370, 48245601976, 715756932697, 11277786883706, 188135296650845
(list; graph; listen)
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OFFSET
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3,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
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(4)=6 because we have (124)3, (134)2, (234)1, 4(123), 3(124) and 2(134), where the parentheses surround runs of length 3.
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CROSSREFS
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Cf. A008304.
Sequence in context: A049685 A122371 A083067 this_sequence A152107 A143023 A078009
Adjacent sequences: A000399 A000400 A000401 this_sequence A000403 A000404 A000405
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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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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