Hi guys. To day i meet a problem that : give you integer t is number of test case (t <= 10) each line have an interger n ( n <= 1e6) , Count the number of ways to choose a distinct (at least 1) set of numbers (elements in the ascending set) such that they form an arithmetic progression.

example : if n = 3 , the answer is 7 : (1,2,3,12,13,23,123)

Hi everyone. i have to solve a problem like that finding the last three digits before the decimal point for the number (3+sqrt(5))^n with n <= 2e9. I thinked but don't have the idea about this problem. So thank you if you help me to solve and i want to know that if with anyone number such is not integer number. can i finding the last three digits before the decimal point. Very thank you