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A084777
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a(n) = sum of absolute-valued coefficients of (1+2x-2x^2)^n.
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2
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1, 5, 17, 73, 273, 881, 3785, 13081, 48737, 184321, 632193, 2526305, 8854081, 32077921, 124093025, 428178641, 1638563969, 5878561921, 21469361537, 82252171393, 286863949025, 1061000856417, 3998983314849, 14361380710817
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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..23.
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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-2*x^2)^n, k, x))); print1(S", "))
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CROSSREFS
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Sequence in context: A354040 A187823 A297625 * A149717 A149718 A149719
Adjacent sequences: A084774 A084775 A084776 * A084778 A084779 A084780
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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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