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A012687 sech(tanh(x)*arctan(x))=1-12/4!*x^4+480/6!*x^6-18480/8!*x^8... 0
1, 0, -12, 480, -18480, 176640, 149396544, -38742692352, 6743113079040, -363222941859840, -455485254371044352, 322516524038804660224, -135316725169663246512128, 19655917963465137568481280 (list; graph; refs; listen; history; internal format)
OFFSET

0,3

CROSSREFS

Sequence in context: A178217 A003749 A012395 * A012467 A009083 A012681

Adjacent sequences:  A012684 A012685 A012686 * A012688 A012689 A012690

KEYWORD

sign

AUTHOR

Patrick Demichel (dml(AT)hpfrcu03.france.hp.com)

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Last modified February 13 15:49 EST 2012. Contains 205521 sequences.