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A116821
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Number of permutations of length n which avoid the patterns 1234, 1324, 1432.
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0
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1, 2, 6, 21, 76, 278, 1019, 3734, 13678, 50100, 183514, 672230, 2462490, 9020556, 33043996, 121046420, 443416116, 1624318192, 5950189652, 21796689568, 79845470136, 292489332488, 1071444754512, 3924908494984, 14377695776152
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: A(x) = -{x(-1+6x-10x^4+17x^3+x^6-14x^2)}/{34x^4-38x^3+24x^2-14x^5-8x+1+2x^6}
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MATHEMATICA
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LinearRecurrence[{8, -24, 38, -34, 14, -2}, {1, 2, 6, 21, 76, 278, 1019}, 30] (* Harvey P. Dale, Apr 20 2024 *)
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CROSSREFS
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KEYWORD
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nonn,easy,changed
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AUTHOR
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STATUS
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approved
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