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A179281
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E.g.f. equals the imaginary part of the series F(x) = 1 + x*F(x)^i where i=sqrt(-1).
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2
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0, 0, 2, -3, -56, 720, 360, -175770, 2811520, 27714960, -2332820800, 36227931300, 1242856742400, -79410400212000, 881326533651200, 97641790837227000, -5371510570250240000, 7482518858066928000, 12885336165384393984000
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = imaginary part of C(i*n,n)/(i*n-n+1).
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EXAMPLE
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E.g.f.: 2*x^2/2! - 3*x^3/3! - 56*x^4/4! + 720*x^5/5! + 360*x^6/6! + ...
E.g.f. equals the imaginary part of F(x) = 1 + x*F(x)^i where
F(x) = 1 + x + i*x^2 - (3 + i)*x^3/2 + (6 - 7*i)*x^4/3 + (35 + 72*i)*x^5/12 - (31 - i)*x^6/2 + (1043 - 2511*i)*x^7/72 + (4074 + 4393*i)*x^8/63 - (52299 - 17108*i)*x^9/224 + (171324 - 1458013*i)*x^10/2268 + (53576369 + 32934483*i)*x^11/36288 - (1811381 - 1198743*i)*x^12/462 + ...
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PROG
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(PARI) {a(n)=n!*imag(binomial(I*n, n)/((I-1)*n+1))}
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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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