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Search: id:A009123
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| A009123 |
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Expansion of cosh(ln(1+sin(x))). |
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+0
3
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| 1, 0, 1, -3, 8, -30, 136, -693, 3968, -25260, 176896, -1351383, 11184128, -99680490, 951878656, -9695756073, 104932671488, -1202439837720, 14544442556416, -185185594118763, 2475749026562048, -34674437196568950
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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a(2n) = 1/2*A000182(n+1), a(2n+1) = A012007(n+1) = A009567(2n+1)+1.
|a(n)| = number of even alternating permutations on n letters (offset 1). - Vladeta Jovovic (vladeta(AT)eunet.rs), May 20 2007
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MATHEMATICA
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Cosh[ Log[ 1+Sin[ x ] ] ]
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CROSSREFS
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Cf. A000111.
Sequence in context: A096161 A161779 A074501 this_sequence A066764 A059171 A078619
Adjacent sequences: A009120 A009121 A009122 this_sequence A009124 A009125 A009126
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KEYWORD
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sign,easy
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AUTHOR
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R. H. Hardin (rhhardin(AT)att.net)
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EXTENSIONS
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Extended with signs Mar 15 1997 by Olivier Gerard.
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