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A113679
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Expansion of (1-x-2x^2)/(1-x).
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2
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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
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OFFSET
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0,3
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COMMENTS
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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:
(End)
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LINKS
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FORMULA
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a(n) = C(0, n) + 2*C(1, n) - 2.
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MATHEMATICA
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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 *)
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CROSSREFS
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KEYWORD
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easy,sign
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AUTHOR
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STATUS
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approved
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