The first term of a sequence is 1111. Each succeeding term is the sum of the cubes of the digits of the previous term. What is the 1729-th term of the sequence?
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We can see that,
a 1 = 1 1 1 1
a 2 = 1 3 + 1 3 + 1 3 + 1 3 = 4
a 3 = 4 3 = 6 4
a 4 = 6 3 + 4 3 = 2 8 0
a 5 = 2 3 + 8 3 + 0 3 = 5 2 0
a 6 = 5 3 + 2 3 + 0 3 = 1 3 3
a 7 = 1 3 + 3 3 + 3 3 = 5 5
a 8 = 5 3 + 5 3 = 2 5 0
a 9 = 2 3 + 5 3 + 0 3 = 1 3 3
and the series continues so on. The 1 7 2 8 t h o r a 1 7 2 8 term will be the same as a 6 so the 1 7 2 9 t h o r a 1 7 2 9 term will be the same as a 7 a 1 7 2 9 = a 7 = 5 5