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A012131
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cosh(arcsin(tanh(x)))=1+1/2!*x^2-3/4!*x^4+21/6!*x^6-263/8!*x^8...
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1
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1, 1, -3, 21, -263, 4841, -99723, -199939, 501445617, -101818966319, 19731909099757, -4192563651606299, 1009030667701246697, -277080625752723191879, 86724157841631252590437
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| Observe that arcsin(tanh(x)) = int {0..x} 1/cosh(t) so the generating function for this sequence is cosh( int {0..x} 1/cosh(t) ). Note the similarity to the generating function for A000364: cosh( int {0..x} 1/cos(t) ) = 1+x^2/2!+5*x^4/4!+61*x^6/6!+... - Peter Bala, Aug 24 2011.
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CROSSREFS
| Sequence in context: A205319 A179504 A197716 * A098278 A066206 A130032
Adjacent sequences: A012128 A012129 A012130 * A012132 A012133 A012134
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KEYWORD
| sign
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AUTHOR
| Patrick Demichel (dml(AT)hpfrcu03.france.hp.com)
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