A000819 - OEIS

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A000819

Expansion of cos^2 x /cos 2x.

1, 2, 40, 1952, 177280, 25866752, 5535262720, 1633165156352, 635421069967360, 315212388819402752, 194181169538675507200, 145435130631317935357952, 130145345400688287667978240, 137139396592145493713802493952 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	LINKS	`R. J. Mathar, Table of n, a(n) for n = 1..200`
	FORMULA	`E.g.f.: cos(x)^2/cos(2x)=1/Q(0)+1/2; Q(k)=1+1/(1-2(x^2)/(2(x^2)-(k+1)*(2k+1)/Q(k+1))); (continued fraction). - Sergei N. Gladkovskii, Nov 18 2011`
	CROSSREFS	`Essentially the same as A000816.` `Second column of array A103905.` `Sequence in context: A198248 A163826 A000816 * A060079 A052502 A104134` `Adjacent sequences: A000816 A000817 A000818 * A000820 A000821 A000822`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com).`

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Last modified February 16 20:59 EST 2012. Contains 205968 sequences.