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Search: id:A116725
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| A116725 |
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Number of permutations of length n which avoid the patterns 132, 3421, 4231. |
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+0
2
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| 1, 2, 5, 12, 26, 52, 99, 184, 340, 632, 1189, 2268, 4382, 8556, 16839, 33328, 66216, 131888, 263113, 525428, 1049906, 2098692, 4196075, 8390632, 16779516, 33557032, 67111789, 134221004, 268439110, 536874972
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.
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FORMULA
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G.f.: A(x) = -{(x^4-6x^3+7x^2-4x+1)x}/{(2x-1)(x-1)^4}
Row sums of triangle A134398. Also, binomial transform of [1, 1, 2, 2, 1, 1, 1,...]. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Oct 23 2007
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CROSSREFS
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Cf. A134398.
Sequence in context: A132977 A027927 A116717 this_sequence A026622 A026688 A116726
Adjacent sequences: A116722 A116723 A116724 this_sequence A116726 A116727 A116728
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KEYWORD
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nonn,easy
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AUTHOR
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Lara Pudwell (lpudwell(AT)math.rutgers.edu), Feb 26 2006
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