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A356901
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a(n) = (2*n)! * [x^(2*n)] arctan(x / sqrt(2))^2.
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0
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0, 1, -4, 46, -1056, 40536, -2342880, 190229040, -20655129600, 2890827273600, -506836099929600, 108811461852576000, -28078128329061888000, 8574915159297970560000, -3059025135601894018560000, 1260573112806548772591360000, -594261372327243392714342400000
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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) = (2*n)! * [x^(2*n)] ((log(1 + I*x/sqrt(2)) - log(1 - I*x/sqrt(2)))/2)^2.
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MAPLE
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ser := series(arctan(x / sqrt(2))^2, x, 38):
seq((2*n)! * coeff(ser, x, 2*n), n = 0..17);
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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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