Your question is Marble Removal Game Winner. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Alice and Bob play a game with a pile of n marbles. On each turn, a player removes Xi marbles such that Xi forms a non-increasing sequence. For each n, determine the winner given that X1 is not equal to n. Alice goes first.