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A198804
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Number of closed paths of length n whose steps are 16th roots of unity, U_16(n).
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1
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1, 0, 16, 0, 720, 0, 50560, 0, 4649680, 0, 514031616, 0, 64941883776, 0, 9071319628800, 0, 1369263687414480, 0, 219705672931613440, 0, 37024402443528248320, 0, 6493814173413849784320, 0, 1177304833671218302960000, 0, 219456611569479963675136000, 0
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OFFSET
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0,3
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COMMENTS
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U_16(n), (comment in article) : For each m >= 1, the sequence (U_m(N)), N >= 0 is P-recursive but is not algebraic when m > 2.
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LINKS
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FORMULA
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E.g.f.: ( Sum_{n>=0} x^(2*n)/n!^2 )^8. - Paul D. Hanna, Oct 30 2011
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PROG
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(PARI) {a(n)=n!*polcoeff(sum(m=0, n, x^(2*m)/m!^2+x*O(x^n))^8, n)}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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