def f(n): a=[0];i=1 while n:a+=[i-a[a[a[i-1]]]];i+=1;n-=1 return a[i-1] for i in list(range(21))+[10000]: print(i,f(i))
Standard input is empty
0 0 1 1 2 1 3 2 4 3 5 4 6 4 7 5 8 5 9 6 10 7 11 7 12 8 13 9 14 10 15 10 16 11 17 12 18 13 19 13 20 14 10000 6823