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A154570
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The main diagonal of the successive differences of A154127.
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3
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1, 3, -4, 2, -6, -2, -14, -18, -46, -82, -174, -338, -686, -1362, -2734, -5458, -10926, -21842, -43694, -87378, -174766, -349522, -699054, -1398098, -2796206, -5592402, -11184814, -22369618, -44739246, -89478482, -178956974, -357913938, -715827886
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=a(n-1)+2*a(n-2), n>0.
a(n+2) = 2*(-1)^(n+1)*A140966(n).
a(n+5) = -2*A083582(n).
a(2n+1) = 3-A078008(2n) = 3-A047849(n).
a(2n+2) = -4-A078008(2n+1) = -4-A020988(n).
G.f.: (1+2*x-9*x^2)/((1+x)*(1-2*x)). - R. J. Mathar, Feb 25 2009
a(n)=(1/3)*[10*(-1)^n-2^n]+(9/2)*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Mar 02 2009]
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MATHEMATICA
| f[n_]:=2/(n+1); x=6; Table[x=f[x]; Numerator[x], {n, 0, 5!}](*Absolute Values*) [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 12 2010]
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CROSSREFS
| Sequence in context: A162196 A179297 A133620 * A145961 A082928 A139524
Adjacent sequences: A154567 A154568 A154569 * A154571 A154572 A154573
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KEYWORD
| sign
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Jan 12 2009
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EXTENSIONS
| Edited and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 25 2009
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