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number theory senior
Problem
The first term of a sequence is . Each succeeding term is the sum of the cubes of the digits of the previous term. What is the term of the sequence?
(A)
(B)
(C)
(D)
(E)
Solution
Performing this operation several times yields the results of for the second term, for the third term, and for the fourth term. The sum of the cubes of the digits of equal , a complete cycle. The cycle is, excluding the first term, the , , and terms will equal , , and , following the fourth term. Any term number that is equivalent to will produce a result of . It just so happens that , which leads us to the answer of .
Final answer
E