I need help with all please. Please help ASAP! Thank you so much!

Use pseudocode to write a recursive algorithm for calculating the sum of the first n non-negative integers. You may assume that n will never be less than 0. Does this algorithm use tail-end recursion? (Shouldn't it?) Use pseudocode to write a non-recursive algorithm for calculating the sum of the first n nonnegative integers. Solve the following recurrence relation. (No, I don't want to know what all the numbers are, I want you to find a closed-form formula). a_o = 7 and a_n = (n + 1)a_n-1,n ge 1