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A012509
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-log(cos(x)*cos(x))=2/2!*x^2+4/4!*x^4+32/6!*x^6+544/8!*x^8+...
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1
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0, 2, 4, 32, 544, 15872, 707584, 44736512, 3807514624, 419730685952, 58177770225664, 9902996106248192, 2030847773013704704, 493842960380415967232, 140503203207887919775744, 46238368375619195682947072, 17427925514250338592341622784, 7458815407441059142195019251712
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Of course this is 2 log(sec(x)), so a(n) = 2*A000182(n).
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EXAMPLE
| x^2+1/6*x^4+2/45*x^6+17/1260*x^8+62/14175*x^10+691/467775*x^12+...
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CROSSREFS
| Sequence in context: A134958 A101460 A118992 * A062740 A122214 A122216
Adjacent sequences: A012506 A012507 A012508 * A012510 A012511 A012512
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KEYWORD
| nonn
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AUTHOR
| Patrick Demichel (dml(AT)hpfrcu03.france.hp.com)
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EXTENSIONS
| Corrected by D. S. McNeil and N. J. A. Sloane, Dec 17 2011 (The signs were wrong and the initial term was missing)
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