The first if a twisted version of a Fibonacci sequence :P
If a1=1.2 and a2=2.3 and a(n)=a(n-1)+a(n-2)
a3=3.5, a4=5.8, a5=9.3
So the first five terms are: 1.2, 2.3, 3.5, 5.8, 9.3
The second is another modified Fibonacci sequence...
If a3=-5 and a4=3 then:
3=-5+a2, a2=8
-5=8+a1, a1=-13
a5=-5+3=-2
a6=-2+3=1
So the first six terms are -13, 8, -5, 3, -2, 1