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A054127
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a(1) = 2; a(n) = 9*2^(n-2) - n - 2, n>1.
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1
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2, 5, 13, 30, 65, 136, 279, 566, 1141, 2292, 4595, 9202, 18417, 36848, 73711, 147438, 294893, 589804, 1179627, 2359274, 4718569, 9437160, 18874343, 37748710, 75497445, 150994916, 301989859, 603979746, 1207959521
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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G.f.: x * (2-x) * (1-x+x^2) / ( (1-x)^2 * (1-2*x) ). - Joerg Arndt, Dec 01 2014
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MATHEMATICA
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Join[{2}, Table[9*2^(n-2)-n-2, {n, 2, 30}]] (* Harvey P. Dale, Jul 16 2020 *)
LinearRecurrence[{4, -5, 2}, {2, 5, 13, 30}, 30] (* Harvey P. Dale, Aug 01 2021 *)
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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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