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A007452 Expand cos x / exp x and invert nonzero coefficients. 5
1, -1, 0, 3, -6, 30, 0, -630, 2520, -22680, 0, 1247400, -7484400, 97297200, 0, -10216206000, 81729648000, -1389404016000, 0, 237588086736000, -2375880867360000, 49893498214560000, 0, -12623055048283680000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..23.

FORMULA

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

CROSSREFS

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

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

Sequence in context: A024497 A007228 A096155 * A046981 A065943 A275786

Adjacent sequences:  A007449 A007450 A007451 * A007453 A007454 A007455

KEYWORD

sign

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified April 20 22:22 EDT 2019. Contains 322310 sequences. (Running on oeis4.)