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A028860
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a(n+2) = 2 a(n+1) + 2 a(n).
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9
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-1, 1, 0, 2, 4, 12, 32, 88, 240, 656, 1792, 4896, 13376, 36544, 99840, 272768, 745216, 2035968, 5562368, 15196672, 41518080, 113429504, 309895168, 846649344, 2313089024, 6319476736, 17265131520
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 924
Tanya Khovanova, Recursive Sequences
Index entries for sequences related to linear recurrences with constant coefficients
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FORMULA
| a(n) = 4*A028859(n-4), for n>3.
G.f.: -(1-3x)/(1-2x-2x^2). a(n) = 3*A002605(n-1) -A002605(n). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 27 2008]
If p[i]=fibonacci(2i-4) and if A is the Hessenberg matrix of order n defined by: A[i,j]=p[j-i+1], (i<=j), A[i,j]=-1, (i=j+1), and A[i,j]=0 otherwise. Then, for n>=1, a(n-1)= det A. [From Milan R. Janjic (agnus(AT)blic.net), May 08 2010]
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MATHEMATICA
| (With a different offset) M = {{0, 2}, {1, 2}} v[1] = {0, 1} v[n_] := v[n] = M.v[n - 1] a = Table[Abs[v[n][[1]]], {n, 1, 50}] - Roger L. Bagula (rlbagulatftn(AT)yahoo.com), May 29 2005
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PROG
| (Haskell)
a028860 n = a028860_list !! n
a028860_list =
-1 : 1 : map (* 2) (zipWith (+) a028860_list (tail a028860_list))
-- Reinhard Zumkeller, Oct 15 2011
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CROSSREFS
| Cf. A026150, A030195, A080040, A083337, A106435, A108898, A125145.
Sequence in context: A192531 A109388 A181329 * A152035 A026151 A025178
Adjacent sequences: A028857 A028858 A028859 * A028861 A028862 A028863
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KEYWORD
| sign
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com). Edited by N. J. A. Sloane, Apr 11 2009
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