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A128543
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a(n) = floor(2^(n-2)*3*n).
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5
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1, 6, 18, 48, 120, 288, 672, 1536, 3456, 7680, 16896, 36864, 79872, 172032, 368640, 786432, 1671168, 3538944, 7471104, 15728640, 33030144, 69206016, 144703488, 301989888, 629145600, 1308622848, 2717908992, 5637144576
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Binomial transform of A007310 (assuming offset 0 in both sequences).
a(n) = 4*a(n-1) - 4*a(n-2) for n>3.
G.f.: x*(1+2*x-2*x^2)/(1-2*x)^2. (End)
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MATHEMATICA
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CoefficientList[Series[(1+2*x-2*x^2)/(1-2*x)^2, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 28 2012 *)
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PROG
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(Magma) I:=[1, 6, 18]; [n le 3 select I[n] else 4*Self(n-1)-4*Self(n-2): n in [1..40]]; // Vincenzo Librandi, Jun 28 2012
(Haskell)
a128543 = sum . a134239_row . subtract 1
(Sage) [1]+[3*n*2^(n-2) for n in (2..40)] # G. C. Greubel, Jul 11 2019
(GAP) Concatenation([1], List([2..40], n-> 3*n*2^(n-2))); # G. C. Greubel, Jul 11 2019
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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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EXTENSIONS
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STATUS
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approved
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