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A156591
First differences of A154570.
3
2, -7, 6, -8, 4, -12, -4, -28, -36, -92, -164, -348, -676, -1372, -2724, -5468, -10916, -21852, -43684, -87388, -174756, -349532, -699044, -1398108, -2796196, -5592412, -11184804, -22369628, -44739236, -89478492, -178956964, -357913948, -715827876
OFFSET
0,1
FORMULA
a(n)+a(n+1) = -A000079(n-1), n>0.
a(n+1) = 4*(-1)^(n+1)- A154879(n).
G.f.: (1-3*x)*(2-3*x)/((1+x)*(1-2*x)). a(n) = -2^n/6+20*(-1)^n/3, n>0. - R. J. Mathar, Feb 25 2009
CROSSREFS
Sequence in context: A210965 A189959 A158241 * A233770 A138283 A308682
KEYWORD
sign,easy
AUTHOR
Paul Curtz, Feb 10 2009
EXTENSIONS
Edited by R. J. Mathar, Feb 25 2009
STATUS
approved