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Expand cos x / exp x and invert nonzero coefficients.
5

%I #8 Mar 30 2012 18:41:11

%S 1,-1,0,3,-6,30,0,-630,2520,-22680,0,1247400,-7484400,97297200,0,

%T -10216206000,81729648000,-1389404016000,0,237588086736000,

%U -2375880867360000,49893498214560000,0,-12623055048283680000

%N Expand cos x / exp x and invert nonzero coefficients.

%F a(4n+2) = 0, a(n) = (-1)^[n == 1, 4, 7 mod 8] * n!/2^floor(n/2). - _Ralf Stephan_, Mar 06 2004

%Y Absolute values are essentially the same as A046981, where zeros are replaced by ones.

%Y Cf. A052277, A007019, A046979, A007415, A009775, A092820.

%K sign

%O 0,4

%A _N. J. A. Sloane_.