A000825 - OEIS

A000825

Expansion of cos x (1 + sin x ) /cos 2x.

1, 1, 3, 8, 57, 256, 2763, 17408, 250737, 2031616, 36581523, 362283008, 7828053417, 91620376576, 2309644635483, 31191159799808, 898621108880097, 13753735117275136, 445777636063460643, 7625476699018231808

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

R. J. Mathar, Table of n, a(n) for n = 0..200

FORMULA

a(n) ~ n! * (sqrt(2) + 1 + (sqrt(2)-1)*(-1)^n) * 4^n / Pi^(n+1). - Vaclav Kotesovec, Jun 01 2015

MATHEMATICA

With[{nn=20}, CoefficientList[Series[Cos[x] (1+Sin[x])/Cos[2x], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Nov 08 2013 *)

CROSSREFS

Cf. A000828, A000831.

Bisections are A000281 and (1/2) * A012393.

Sequence in context: A308572 A101361 A104034 * A273433 A132517 A027262

Adjacent sequences: A000822 A000823 A000824 * A000826 A000827 A000828

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

STATUS

approved