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A151642
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Number of permutations of 4 indistinguishable copies of 1..n with exactly 4 adjacent element pairs in decreasing order.
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2
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0, 1, 13840, 4961755, 733059110, 75073622025, 6438673851876, 503519287150295, 37463016470769170, 2712124797724710645, 193396524783642727120, 13675857973300537321251, 962624331855762939745950, 67586399804656292725004385, 4738724382451462432861849980
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OFFSET
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1,3
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LINKS
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Andrew Howroyd, Table of n, a(n) for n = 1..200
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FORMULA
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a(n) = 70^n - (4*n + 1)*35^n + binomial(4*n+1, 2)*15^n - binomial(4*n+1, 3)*5^n + binomial(4*n+1, 4). - Andrew Howroyd, May 07 2020
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PROG
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(PARI) a(n) = {70^n - (4*n + 1)*35^n + binomial(4*n+1, 2)*15^n - binomial(4*n+1, 3)*5^n + binomial(4*n+1, 4)} \\ Andrew Howroyd, May 07 2020
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CROSSREFS
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Column k=4 of A236463.
Sequence in context: A013912 A179582 A325886 * A235004 A263976 A189989
Adjacent sequences: A151639 A151640 A151641 * A151643 A151644 A151645
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, May 29 2009
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EXTENSIONS
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Terms a(8) and beyond from Andrew Howroyd, May 07 2020
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STATUS
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approved
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