a(n) = { if (n==0, return (0), for (k=2, oo, if (fibonacci(k)<=n && n<fibonacci(k+1), return (fibonacci(k) + a(fibonacci(k+1)-n-1))))) } vv = vector(fibonacci(21)-1) for (n=1, #vv, vv[a(n)]=n) print ("0 0") for (n=1, #vv, print (n " " vv[n])) quit