I can't figure this one out, I'm all out of brains.
aₙ = aₙ₋₁ + aₙ₋₂
a₁ = 1; a₂ = -2
I need to find the 4th and the 10th numbers in the sequence and apparently the answers are a₄ = -3 and a₁₀ = -47. I tried an equation system and everything I know on this problem but I can't get those answers. I've never seen a sequence like that and I don't see a common difference here.
I would be very thankful for any help.