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A084778
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a(n) = sum of absolute-valued coefficients of (1+2x-3x^2)^n.
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2
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1, 6, 28, 128, 660, 3016, 13108, 64112, 304068, 1332992, 6514356, 29341384, 131904528, 623547112, 2990903464, 13436119424, 61647598484, 284398511848, 1302463169256, 6195158123688, 28653898573420, 130138400720504
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..21.
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PROG
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(PARI) for(n=0, 40, S=sum(k=0, 2*n, abs(polcoeff((1+2*x-3*x^2)^n, k, x))); print1(S", "))
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CROSSREFS
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Sequence in context: A351053 A171859 A338584 * A287807 A155588 A208439
Adjacent sequences: A084775 A084776 A084777 * A084779 A084780 A084781
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna, Jun 14 2003
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STATUS
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approved
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