Dec 14, 2009
Problem of the Week
for Monday, December 14, 2009
The sequence 1,2,1,0 is called an "autobiographical" sequence because its first digit tells you how many zeros are in the sequence, the next digit counts the number of ones, and so on. (specifically, the digit sequence 1,2,1,0 contains 1 zero, 2 ones, 1 two, and no threes.) It turns out that there are many such sequences. How many can you find?