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A371304
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E.g.f. satisfies A(x) = 1/(1 - x^2*(exp(x*A(x)) - 1)).
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0
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1, 0, 0, 6, 12, 20, 1470, 12642, 70616, 2131992, 39352410, 470186750, 11032124532, 295053244356, 5896487364950, 146264289411450, 4625791393554480, 130492119237611312, 3837833086814864946, 135471306780659593206, 4800394977109827314060
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OFFSET
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0,4
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LINKS
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FORMULA
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a(n) = n! * Sum_{k=0..floor(n/3)} (n-k)! * Stirling2(n-2*k,k)/( (n-2*k)! * (n-2*k+1)! ).
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PROG
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(PARI) a(n) = n!*sum(k=0, n\3, (n-k)!*stirling(n-2*k, k, 2)/((n-2*k)!*(n-2*k+1)!));
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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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