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A304172
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a(n) = 99*2^n - 45 (n>=0).
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2
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54, 153, 351, 747, 1539, 3123, 6291, 12627, 25299, 50643, 101331, 202707, 405459, 810963, 1621971, 3243987, 6488019, 12976083, 25952211, 51904467, 103808979, 207618003, 415236051, 830472147, 1660944339, 3321888723, 6643777491, 13287555027, 26575110099, 53150220243, 106300440531, 212600881107, 425201762259
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OFFSET
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0,1
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COMMENTS
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a(n) is the number of edges in the N-branched phenylacetylene NSB[n], shown pictorially in the Yarahmadi reference (for n=2).
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LINKS
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FORMULA
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G.f.: 9*(6 - x) / ((1 - x)*(1 - 2*x)).
a(n) = 3*a(n-1) - 2*a(n-2) for n>1.
(End)
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MAPLE
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seq(99*2^n-45, n = 0 .. 35);
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PROG
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(PARI) Vec(9*(6 - x) / ((1 - x)*(1 - 2*x)) + O(x^30)) \\ Colin Barker, May 10 2018
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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