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A181655
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Expansion of (1+2x-x^3+x^4)/(1-4x^2+3x^4).
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3
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1, 2, 4, 7, 14, 22, 44, 67, 134, 202, 404, 607, 1214, 1822, 3644, 5467, 10934, 16402, 32804, 49207, 98414, 147622, 295244, 442867, 885734, 1328602, 2657204, 3985807, 7971614, 11957422, 23914844, 35872267, 71744534, 107616802, 215233604
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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G.f.: (1+2*x-x^3+x^4)/((1-x^2)*(1-3*x^2)).
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MATHEMATICA
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CoefficientList[Series[(1+2x-x^3+x^4)/(1-4x^2+3x^4), {x, 0, 40}], x] (* or *) Join[{1}, LinearRecurrence[{0, 4, 0, -3}, {2, 4, 7, 14}, 40]] (* Harvey P. Dale, Jan 11 2012 *)
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PROG
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(PARI) A181655(n)=if(bitand(n, 1), 3^(n\2)*5\2, n, 3^(n\2-1)*5-1, 1) \\ M. F. Hasler, Apr 06 2019
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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