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IKMC 2019 - Grades 11-12 - Set 2 - Self-study Question 28

IKMC · IKMC 2019 - Grades 11-12 - Set 2 - Self-study

Question 28

The sequence starts at $a_1=49$. To obtain $a_{n+1}$, add 1 to the digit sum of $a_n$ and square the result; for example $a_2=(4+9+1)^2=196$. Find $a_{2019}$.
  1. 121
  2. 25
  3. 64
  4. 400
  5. 49