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A012465 cosh(arctan(x)*arctan(x))=1+12/4!*x^4-480/6!*x^6+31248/8!*x^8... 1
1, 0, 12, -480, 31248, -3160320, 462297792, -92467554816, 24237361774848, -8058187934539776, 3312017870282345472, -1648428171351870627840, 976764310209146448384000, -679332936418413117235200000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..13.

MATHEMATICA

nn = 20; Table[(CoefficientList[Series[Cosh[ArcTan[x]^2], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Feb 08 2015 *)

CROSSREFS

Sequence in context: A009168 A012460 A012685 * A012394 A012686 A012466

Adjacent sequences:  A012462 A012463 A012464 * A012466 A012467 A012468

KEYWORD

sign

AUTHOR

Patrick Demichel (patrick.demichel(AT)hp.com)

STATUS

approved

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Last modified October 19 03:13 EDT 2019. Contains 328211 sequences. (Running on oeis4.)