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%I #7 Jun 13 2015 00:53:02
%S -5,-1,-2,-4,-8,-16,-32,-64,-128,-256,-512,-1024,-2048,-4096,-8192,
%T -16384,-32768,-65536,-131072,-262144,-524288,-1048576,-2097152,
%U -4194304,-8388608,-16777216,-33554432,-67108864,-134217728,-268435456,-536870912,-1073741824
%N a(n) = A156591(n) + A156591(n+1).
%C A156591 = 2,-7,6,-8,4,-12,... a(n) is companion to A154589 = 4,-1,-2,-4,-8,.For this kind ,companion of sequence b(n) is first differences a(n), second differences being b(n). Well known case: A131577 and A011782. a(n)+b(n)=A000079 or -A000079. a(n)=A154570(n+2)-A154570(n) ,A154570 = 1,3,-4,2,-6,-2,-14,. See sequence(s) identical to its p-th differences (A130785,A130781,A024495,A000749,A138112(linked to Fibonacci),A139761).
%H Colin Barker, <a href="/A157823/b157823.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (2).
%F a(n) = 2*a(n-1) for n>1. G.f.: -(9*x-5) / (2*x-1). - _Colin Barker_, Feb 03 2015
%o (PARI) Vec(-(9*x-5)/(2*x-1) + O(x^100)) \\ _Colin Barker_, Feb 03 2015
%K sign,easy
%O 0,1
%A _Paul Curtz_, Mar 07 2009
%E Edited by _Charles R Greathouse IV_, Oct 11 2009
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