Question 9
(FRG) A sequence $(a_n)$ is defined by means of the recursion
$$a_1=1,\qquad a_{n+1}=\frac{1+4a_n+\sqrt{1+24a_n}}{16}.$$
Find an explicit formula for $a_n$.
$$a_1=1,\qquad a_{n+1}=\frac{1+4a_n+\sqrt{1+24a_n}}{16}.$$
Find an explicit formula for $a_n$.