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A091154 Numerator of Maclaurin expansion of (t Sqrt[t^2+1]+ArcSinh[t])/2, the arc length of Archimedes' spiral. 0
1, 1, -1, 1, -5, 7, -21, 11, -429, 715, -2431, 4199, -29393, 52003, -185725, 334305, -3231615, 3535767, -64822395, 39803225, -883631595, 1641030105, -407771117, 11435320455, -171529806825, 107492012277, -1215486600363, 2295919134019 (list; graph; refs; listen; history; internal format)
OFFSET

1,5

LINKS

Eric Weisstein's World of Mathematics, Archimedes' Spiral

EXAMPLE

t + t^3/6 - t^5/40 + t^7/112 - (5*t^9)/1152 + (7*t^11)/2816 - ...

CROSSREFS

Denominators are in A002595

Sequence in context: A192422 A120035 A198302 * A057424 A027152 A076197

Adjacent sequences:  A091151 A091152 A091153 * A091155 A091156 A091157

KEYWORD

sign,easy

AUTHOR

Eric Weisstein (eric(AT)weisstein.com), Dec 22, 2003

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Last modified February 17 18:01 EST 2012. Contains 206061 sequences.