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A097072
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Expansion of (1-2x+2x^2)/((1-x^2)(1-2x)).
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0
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1, 0, 3, 4, 11, 20, 43, 84, 171, 340, 683, 1364, 2731, 5460, 10923, 21844, 43691, 87380, 174763, 349524, 699051, 1398100, 2796203, 5592404, 11184811, 22369620, 44739243, 89478484, 178956971, 357913940, 715827883, 1431655764, 2863311531
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| a(n)=2*2^n/3-1/2+5(-1)^n/6; a(n)=sum{k=0..n, (2^k-1+0^k)(-1)^(n-k) }; a(n)=A001045(n+1)-A000035(n).
a(n) = a(n-1) + 2*a(n-2) +1, n>1 [From Gary Detlefs (gdetlefs(AT)aol.com), Jun 20 2010]
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MATHEMATICA
| CoefficientList[Series[(1-2x+2x^2)/((1-x^2)(1-2x)), {x, 0, 50}], x] (* From Harvey P. Dale, Mar 09 2011 *)
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CROSSREFS
| Cf. A000975.
Sequence in context: A060285 A025079 A036652 * A049977 A000677 A110865
Adjacent sequences: A097069 A097070 A097071 * A097073 A097074 A097075
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Jul 22 2004
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