%I A131183
%S A131183 1,1,2,1,2,2,4,2,8,4,12,8,96,12,108,96,10368,108,10476,10368,108615168,
%T A131183 10476,108625644,108615168,11798392572168192,108625644,
%U A131183 11798392680793836,11798392572168192,139202068568601556987554268864512
%N A131183 a(n) = a(n-1)+a(n-2) if n == 3 mod 4; a(n) = a(n-1)-a(n-2) if n == 0 
               mod 4; a(n) = a(n-1)*a(n-2) if n == 1 mod 4; and a(n) = a(n-1)/a(n-2) 
               if n == 2 mod 4; with a(1))=a(2)=1
%C A131183 If S(n)=a(4n-1) (i.e. term "+"), R(n)=a(4n) (i.e. "-"), P(n)=a(4n+1), 
               D(n)=a(4n+2) then D(n)=S(n), P(n)= S(n+1)-S(n), R(n+1)=P(n)=S(n+1)-S(n). 
               - Jose Ramon Real (joseramonreal(AT)yahoo.es), Nov 10 2007
%e A131183 a(3)=a(2)+a(1)=1+1=2
%e A131183 a(4)=a(3)-a(2)=2-1=1
%e A131183 a(5)=a(4)*a(3)=1*2=2
%e A131183 a(6)=a(5)/a(4)=2/1=2
%p A131183 A131183 := proc(n) option remember ; if n <= 2 then 1 ; elif n mod 4 
               = 3 then A131183(n-1)+A131183(n-2) ; elif n mod 4 = 0 then A131183(n-1)-A131183(n-2) 
               ; elif n mod 4 = 1 then A131183(n-1)*A131183(n-2) ; else A131183(n-1)/
               A131183(n-2) ; fi ; end: seq(A131183(n),n=1..35) ; - R. J. Mathar 
               (mathar(AT)strw.leidenuniv.nl), Oct 28 2007
%Y A131183 Sequence in context: A054541 A102722 A020475 this_sequence A133770 A163373 
               A117193
%Y A131183 Adjacent sequences: A131180 A131181 A131182 this_sequence A131184 A131185 
               A131186
%K A131183 easy,nonn
%O A131183 1,3
%A A131183 Jose Ramon Real (joseramonreal(AT)yahoo.es), Oct 22 2007
%E A131183 More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 28 2007