The sequence (an) satisfies a1=3 and
an= (an-1-1)/(an-1+1) for all n≥2
Find a100
The pattern is
[ 3 1/2 -1/3 -2 ] [ 3 1/2 -1/3 -2 ]
Notice that the pattern repeats every 4 terms
Then a100 = -2
+79 
