def _chain( self, n ):
t= n
visited= set()
while t not in self.memoized:
t= sum( d*d for d in digits(t) )
visited.add(t)
# Set all the numbers in this chain to point to the same result
for u in visited:
self.memoized[u]= self.memoized[t]
return self.memoized[t]
def _chain( self, n ):
while self.memoized[n] == 0:
n= sum( d*d for d in digits(n) )
return self.memoized[n]