1/an=1/2+1/(4*a(n-1))
bn=1/an
bn=1/2+1/4*b(n-1)
bn=1/4(b(n-1)+2)
bn+x=1/4(b(n-1)+x)
bn=1/4*b(n-1)-3x/4
-3x/4=2,x=-8/3
bn-8/3=(1/4)*(b(n-1)-8/3)
b1=1
bn-3/8=(b1-3/8)*(1/4)^(n-1)
bn-3/8=5/8*(1/4)^(n-1)
bn=5/8*(1/4)^(n-1)+3/8
an=1/(5/8*(1/4)^(n-1)+3/8)
1/an=1/2+1/(4*a(n-1))
bn=1/an
bn=1/2+1/4*b(n-1)
bn=1/4(b(n-1)+2)
bn+x=1/4(b(n-1)+x)
bn=1/4*b(n-1)-3x/4
-3x/4=2,x=-8/3
bn-8/3=(1/4)*(b(n-1)-8/3)
b1=1
bn-3/8=(b1-3/8)*(1/4)^(n-1)
bn-3/8=5/8*(1/4)^(n-1)
bn=5/8*(1/4)^(n-1)+3/8
an=1/(5/8*(1/4)^(n-1)+3/8)