a1=b1
a2n+1=b2n+1
a2n+1-a1=b2n+1-b1=2nd=b1(q^2n-1)=b1(q^n+1)(q^n-1)
nd=b1(q^n+1)(q^n-1)/2
an+1-bn+1=a1+nd-b1*q^n=b1+b1(q^n+1)(q^n-1)/2-b1*q^n=b1(q^n+1)(q^n-1)/2-b1(q^n-1)=b1(q^n-1)^2/2
a1=b1>0
an+1-bn+1=b1(q^n-1)^2/2>=0
an+1>=bn+1
a1=b1
a2n+1=b2n+1
a2n+1-a1=b2n+1-b1=2nd=b1(q^2n-1)=b1(q^n+1)(q^n-1)
nd=b1(q^n+1)(q^n-1)/2
an+1-bn+1=a1+nd-b1*q^n=b1+b1(q^n+1)(q^n-1)/2-b1*q^n=b1(q^n+1)(q^n-1)/2-b1(q^n-1)=b1(q^n-1)^2/2
a1=b1>0
an+1-bn+1=b1(q^n-1)^2/2>=0
an+1>=bn+1