A012821 - OEIS

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A012821

exp(sec(x)*arcsinh(x))=1+x+1/2!*x^2+3/3!*x^3+9/4!*x^4+45/5!*x^5...

1, 1, 1, 3, 9, 45, 225, 1071, 6993, 56697, 467745, 3279419, 29529753, 376156261, 4297350785, 35274762407, 378759492257, 8003761282417, 122599030798017, 853554115621363, 8002975063348265, 450081179390735645 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,4`
	COMMENTS	`The first negative number is a(24)= -686072407102337430543.`
	LINKS	`Table of n, a(n) for n=0..21.`
	CROSSREFS	`Sequence in context: A192891 A068100 A262129 * A229813 A262130 A262131` `Adjacent sequences: A012818 A012819 A012820 * A012822 A012823 A012824`
	KEYWORD	`sign`
	AUTHOR	`Patrick Demichel (patrick.demichel(AT)hp.com)`
	STATUS	`approved`

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Last modified August 18 12:37 EDT 2017. Contains 290720 sequences.