%I A053602
%S A053602 0,1,1,2,1,3,2,5,3,8,5,13,8,21,13,34,21,55,34,89,55,144,89,233,144,
%T A053602 377,233,610,377,987,610,1597,987,2584,1597,4181,2584,6765,4181,10946,
%U A053602 6765,17711,10946,28657,17711,46368,28657,75025,46368,121393,75025
%N A053602 a(n)=a(n-1)-(-1)^n*a(n-2), a(0)=0, a(1)=1.
%C A053602 If b(0)=0, b(1)=1 and b(n)=b(n-1)+(-1)^n*b(n-2), then a(n)=b(n+3) [From 
               Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Oct 03 2009]
%H A053602 <a href="Sindx_Tu.html#2wis">Index entries for two-way infinite sequences</
               a>
%F A053602 G.f.: x*(1+x+x^2)/(1-x^2-x^4). a(n)=a(n-2)+a(n-4).
%F A053602 a(2n)=F(n), a(2n-1)=F(n+1) where F() is Fibonacci sequence.
%F A053602 Also a(n) can be defined as follow: a(3)=1, a(4)=2, for n>4 a(n+2)=a(n+1)+sign(a(n)-a(n+1))*a(n) 
               - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 08 2002
%F A053602 a(n) = A079977(n-1) + A079977(n-2) + A079977(n-3), n>2. - Ralf Stephan, 
               Apr 26 2003
%F A053602 a(1) = 0, a(2) = 1; a(2n+1) = a(2n)-a(2n-1) a(2n+2) = a(2n) + a(2n+1). 
               - Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jul 21 2005
%o A053602 (PARI) a(n)=fibonacci(n\2+n%2*2)
%Y A053602 a(3-n)=A051792(n). Cf. A000045.
%Y A053602 Sequence in context: A114209 A132091 A051792 this_sequence A123231 A058736 
               A097451
%Y A053602 Adjacent sequences: A053599 A053600 A053601 this_sequence A053603 A053604 
               A053605
%K A053602 nonn,easy
%O A053602 0,4
%A A053602 Michael Somos, Jan 17 2000