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A009380 Expansion of log(1+tan(x)/cos(x)). 0
0, 1, -1, 7, -26, 185, -1336, 12367, -129296, 1558865, -21045376, 316097527, -5218370816, 94003171145, -1834192393216, 38543705698687, -867785366030336, 20840298552277025, -531767959826169856, 14366953364916735847 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
FORMULA
a(n) ~ (n-1)! * (-1)^(n+1) / (arctan(sqrt((sqrt(5)-1)/2)))^n. - Vaclav Kotesovec, Jan 23 2015
MATHEMATICA
Log[ 1+Tan[ x ]/Cos[ x ]]
CoefficientList[Series[Log[1 + Sec[x]*Tan[x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)
CROSSREFS
Sequence in context: A026683 A197053 A009375 * A183329 A342930 A166406
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved

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Last modified July 22 00:58 EDT 2024. Contains 374478 sequences. (Running on oeis4.)