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A154570 The main diagonal of the successive differences of A154127. 4
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; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..32.

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. - Paolo P. Lava, Mar 02 2009

MATHEMATICA

f[n_]:=2/(n+1); x=6; Table[x=f[x]; Numerator[x], {n, 0, 5!}](*Absolute Values*) (* Vladimir Joseph Stephan Orlovsky, Mar 12 2010 *)

CROSSREFS

Sequence in context: A162196 A179297 A133620 * A145961 A082928 A139524

Adjacent sequences:  A154567 A154568 A154569 * A154571 A154572 A154573

KEYWORD

sign

AUTHOR

Paul Curtz, Jan 12 2009

EXTENSIONS

Edited and extended by R. J. Mathar, Feb 25 2009

STATUS

approved

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Last modified October 23 05:50 EDT 2018. Contains 316519 sequences. (Running on oeis4.)