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A077993
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Expansion of 1/(1+2*x+2*x^2+2*x^3).
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3
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1, -2, 2, -2, 4, -8, 12, -16, 24, -40, 64, -96, 144, -224, 352, -544, 832, -1280, 1984, -3072, 4736, -7296, 11264, -17408, 26880, -41472, 64000, -98816, 152576, -235520, 363520, -561152, 866304, -1337344, 2064384, -3186688, 4919296, -7593984, 11722752, -18096128, 27934720, -43122688
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OFFSET
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0,2
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LINKS
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FORMULA
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MATHEMATICA
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LinearRecurrence[{-2, -2, -2}, {1, -2, 2}, 50] (* or *) CoefficientList[ Series[1/(1+2*x+2*x^2+2*x^3), {x, 0, 50}], x] (* G. C. Greubel, Jun 27 2019 *)
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PROG
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(PARI) my(x='x+O('x^50)); Vec(1/(1+2*x+2*x^2+2*x^3)) \\ G. C. Greubel, Jun 27 2019
(Magma) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( 1/(1+2*x+2*x^2+2*x^3) )); // G. C. Greubel, Jun 27 2019
(Sage) (1/(1+2*x+2*x^2+2*x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Jun 27 2019
(GAP) a:=[1, -2, 2];; for n in [4..50] do a[n]:=-2*(a[n-1]+a[n-2]+a[n-3]); od; a; # G. C. Greubel, Jun 27 2019
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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