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A113679 Expansion of (1-x-2x^2)/(1-x). 2
1, 0, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Contribution from Gary W. Adamson, Mar 06 2012 (Start):

Signed (1, 0, -2, 2, -2, 2,...) and convolved with the Toothpick sequence A139250 = A151548: (1, 3, 5, 7, 5, 11,...).  The inverse of (1, 0, -2, 2, -2,...) = A151575: (1, 0, 2, -2, 6, -10, 22,...).

The unsigned sequence convolved with:

(1, 2, 3,...) = A002523, (n^2 + 1). Convolved with:

(A001045) = ....A097064: (1, 1, 5, 9, 21, 41,...)

(End)

LINKS

Table of n, a(n) for n=0..66.

FORMULA

a(n)=C(0, n)+2*C(1, n)-2.

MATHEMATICA

CoefficientList[Series[(1-x-2x^2)/(1-x), {x, 0, 80}], x] (* or *) Join[{1, 0}, PadRight[{}, 80, -2]] (* Harvey P. Dale, Mar 05 2012 *)

CROSSREFS

Cf. A113680.

Cf. A139250, A151548, A151575, A002523. - Gary W. Adamson, Mar 06 2012

Sequence in context: A044930 A032545 A231560 * A262438 A004218 A044931

Adjacent sequences:  A113676 A113677 A113678 * A113680 A113681 A113682

KEYWORD

easy,sign

AUTHOR

Paul Barry, Nov 04 2005

STATUS

approved

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Last modified September 20 16:48 EDT 2019. Contains 327242 sequences. (Running on oeis4.)