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A008353
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2^n*(2^(n+1) - n - 1).
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4
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1, 4, 20, 96, 432, 1856, 7744, 31744, 128768, 519168, 2085888, 8364032, 33501184, 134103040, 536625152, 2146959360, 8588820480, 34357379072, 137433972736, 549745328128, 2199001235456, 8796046884864, 35184275619840, 140737287028736, 562949533990912
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = sum{k=0..n+1, C(2n+2, 2k)-2k(n-k+1)*C(n+1, k)/n}, n>0. - Paul Barry, Feb 24 2005
a(n) = 8*a(n-1)-20*a(n-2)+16*a(n-3). - Colin Barker, Feb 26 2015
G.f.: -(8*x^2-4*x+1) / ((2*x-1)^2*(4*x-1)). - Colin Barker, Feb 26 2015
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PROG
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(PARI) Vec(-(8*x^2-4*x+1)/((2*x-1)^2*(4*x-1)) + O(x^100)) \\ Colin Barker, Feb 26 2015
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CROSSREFS
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a(n) = 1 for n=0, 4 * A008464(n-2) else.
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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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