main =>
  println("First 61 fusc numbers:"),
  println([fusc(I) : I in 0..60]),
  nl,
  println("Points in the sequence whose length is greater than any previous fusc number length:\n"),
  println("   Index     fusc  Len"),
  largest_fusc_string(20_000_000).

table
fusc(0) = 0.
fusc(1) = 1.
fusc(N) = fusc(N//2), even(N) => true.
fusc(N) = fusc((N-1)//2) + fusc((N+1)//2) => true.

largest_fusc_string(Limit) =>
  largest_fusc_string(0,Limit,0).

largest_fusc_string(Limit,Limit,_).
largest_fusc_string(N,Limit,LargestLen) :-
  N <= Limit,
  F = fusc(N),
  Len = F.to_string.len,
  (Len > LargestLen ->
     printf("%8d %8d %4d\n",N,F,Len),
     LargestLen1 = Len
   ;
     LargestLen1 = LargestLen
  ),
  largest_fusc_string(N+1,Limit,LargestLen1).