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 A012821 Expansion of e.g.f. exp(sec(x)*arcsinh(x)). 2
 1, 1, 1, 3, 9, 45, 225, 1071, 6993, 56697, 467745, 3279419, 29529753, 376156261, 4297350785, 35274762407, 378759492257, 8003761282417, 122599030798017, 853554115621363, 8002975063348265, 450081179390735645 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS The first negative number is a(24) = -686072407102337430543. LINKS Andrew Howroyd, Table of n, a(n) for n = 0..200 EXAMPLE exp(sec(x)*arcsinh(x)) = 1 + x + 1/2!*x^2 + 3/3!*x^3 + 9/4!*x^4 + 45/5!*x^5 + ... PROG (PARI) seq(n)={my(x='x+O('x^n)); Vec(serlaplace(exp(asinh(x)/cos(x))))} \\ Andrew Howroyd, Feb 25 2018 CROSSREFS Sequence in context: A068100 A327648 A262129 * A229813 A262130 A262131 Adjacent sequences:  A012818 A012819 A012820 * A012822 A012823 A012824 KEYWORD sign AUTHOR Patrick Demichel (patrick.demichel(AT)hp.com) STATUS approved

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Last modified May 26 17:16 EDT 2022. Contains 354092 sequences. (Running on oeis4.)