Mathematics - Permutation & Combination Question with Solution | TestHub

Let $x_1{x}_2{x}_3{x}_4{x}_5{x}_4{x}_3{x}_2{x}_1$ be a nine digit palindrome such that either the sequence $\left(x_1,x_2,x_3,x_4,x_5\right)$ is a strictly ascending or strictly descending. Then the number of such palindromes is