Basically fibonachi is the 1st term+term before first term=2nd term 3rd term=1st term+2nd term 4th term=2nd term+3rd term etc
starting with t1=0 and t2=1 0,1 add them to get next 0+1=1 now we have 0,1,1 1+1=2 now we have 0,1,1,2 1+2=3 now we have 0,1,1,2,3 2+3=5 now we have 0,1,1,2,3,5 3+5=8 now we have 0,1,1,2,3,5,8 5+8=13 now we have 0,1,1,2,3,5,8,13 8+13=21 now we have 0,1,1,2,3,5,8,13,21