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A373542
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Expansion of e.g.f. exp(x * sqrt(1-x^2)).
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0
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1, 1, 1, -2, -11, -44, -59, -104, 1513, -4976, 14761, -1005344, -594659, -120135872, -8409491, -19661062784, 461914321, -4406419844864, 8555830993, -1268264427577856, -595229416379, -455779307821067264, -13631036685419, -200172063313066452992
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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/2)} (-1)^k * binomial(n/2-k,k)/(n-2*k)!.
a(n) == 1 mod 3.
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PROG
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(PARI) a(n) = n!*sum(k=0, n\2, (-1)^k*binomial(n/2-k, k)/(n-2*k)!);
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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