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A012609
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Expansion of e.g.f. sech(arcsinh(x)*arcsin(x)) in powers of x^4.
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1
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1, -12, 3472, -20044992, -47937777408, -20305698249280512, -2854719816291959009280, -1250271985277826533770444800, -852308886538376231161133484933120, -1020041468410487908146642041792342261760, -1902990477565541776130152995745141108333608960
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OFFSET
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0,2
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LINKS
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EXAMPLE
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1 - 12/4!*x^4 + 3472/8!*x^8 - 20044992/12!*x^12 ...
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PROG
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(PARI) a(n)={my(x=x+O(x*x^(4*n))); polcoef(serlaplace(1/cosh(asinh(x)*asin(x))), 4*n)} \\ Andrew Howroyd, Nov 05 2019
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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Patrick Demichel (patrick.demichel(AT)hp.com)
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EXTENSIONS
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STATUS
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approved
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