%I A122803
%S A122803 1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,
%T A122803 262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,
%U A122803 134217728,268435456,536870912,1073741824,2147483648,4294967296
%V A122803 1,-2,4,-8,16,-32,64,-128,256,-512,1024,-2048,4096,-8192,16384,-32768,
               65536,-131072,
%W A122803 262144,-524288,1048576,-2097152,4194304,-8388608,16777216,-33554432,67108864,
%X A122803 -134217728,268435456,-536870912,1073741824,-2147483648,4294967296
%N A122803 Powers of -2.
%C A122803 Sum_{n>=0} 1/a(n) = 2/3 [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), 
               Mar 01 2009]
%H A122803 Franklin T. Adams-Watters, <a href="b122803.txt">Table of n, (-2)^n for 
               n = 0..1000</a>
%H A122803 <a href="Sindx_Rea.html#recLCC">Index entries for sequences related to 
               linear recurrences with constant coefficients</a>
%H A122803 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/
               RecursiveSequences.html">Recursive Sequences</a>
%F A122803 a(n) = (-2)^n.
%F A122803 a(n) = - 4a(n-1) - 4a(n-2). - Tanya Khovanova (tanyakh(AT)yahoo.com), 
               Feb 01 2007
%F A122803 a(n)=-2*a(n-1), n>0 ; a(0)=1 . G.f.: 1/(1+2x). [From Philippe DELEHAM 
               (kolotoko(AT)wanadoo.fr), Nov 19 2008]
%p A122803 a:=n->mul(-2, k=0..n): seq(a(n), n=-1..31); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Jan 22 2008
%Y A122803 Cf. A000079 (powers of 2).
%Y A122803 Sequence in context: A141531 A166444 A084633 this_sequence A000079 A120617 
               A050732
%Y A122803 Adjacent sequences: A122800 A122801 A122802 this_sequence A122804 A122805 
               A122806
%K A122803 easy,sign
%O A122803 0,2
%A A122803 Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Sep 11 2006