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A115341
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a(n) = abs(A154879(n+1)).
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17
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2, 4, 0, 8, 8, 24, 40, 88, 168, 344, 680, 1368, 2728, 5464, 10920, 21848, 43688, 87384, 174760, 349528, 699048, 1398104, 2796200, 5592408, 11184808, 22369624, 44739240, 89478488, 178956968, 357913944, 715827880, 1431655768, 2863311528
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| General form: a(n)=2^n-a(n-1). Cf. A001045, A078008, A097073 [From Vladimir Orlovsky, Dec 11 2008]
For n>=1, a(n) is a(n) is the number of generalized compositions of n +3 when there are i^2-2*i-1 different types of i, (i=1,2,...). [From Milan R. Janjic (agnus(AT)blic.net), Sep 24 2010]
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..1000
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FORMULA
| a(n) = (2^(n+1)-8*(-1)^n)/3, n>0.
a(n) = a(n-1)+2*a(n-2), n>2.
G.f.: 2+4*x*(1-x)/((1+x)*(1-2*x)).
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MATHEMATICA
| g0[n_] = 2 - Sum[(-1)^(i + 1)/Sqrt[2]^(2*i), {i, 0, n}] f[x_] = ZTransform[g0[n], n, x] g[n_] = InverseZTransform[f[1/x], x, n] a0 = Table[Abs[g[n]], {n, 1, 25}]
k=0; lst={k}; Do[k=2^n-k; AppendTo[lst, k], {n, 3, 5!}]; lst [From Vladimir Orlovsky, Dec 11 2008]
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CROSSREFS
| Cf. A001045, A078008, A097073 [From Vladimir Orlovsky, Dec 11 2008]
Sequence in context: A137511 A011166 A181274 * A101160 A103191 A071607
Adjacent sequences: A115338 A115339 A115340 * A115342 A115343 A115344
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KEYWORD
| nonn
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AUTHOR
| Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Mar 06 2006
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EXTENSIONS
| Edited by the Associate Editors of the OEIS, Aug 21 2009
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