Hello,
A(n)=6+(n+1)^(-2)=6+1/(n+1)²
[tex] A_{4} =6+ \dfrac{1}{(4+1)^2} =6+ \dfrac{1}{25}= \dfrac{151}{25} \\
A_{6} =6+ \dfrac{1}{(6+1)^2} =6+ \dfrac{1}{49}= \dfrac{295}{49} \\
A_{13} =6+ \dfrac{1}{(13+1)^2} =6+ \dfrac{1}{196}= \dfrac{1177}{196} \\
[/tex]
