What is the value of 'X' in the sequence 2, 7, 22, 67, 202, X, 1822?

What is the value of 'X' in the sequence 2, 7, 22, 67, 202, X, 1822?
  1. 603
  2. 605
  3. 607
  4. 608

Solution

Each term is obtained from the previous by multiplying by 3 and adding 1: $2 \times 3 + 1 = 7$, $7 \times 3 + 1 = 22$, $22 \times 3 + 1 = 67$, $67 \times 3 + 1 = 202$, $202 \times 3 + 1 = 607$, $607 \times 3 + 1 = 1822$. Hence X = 607.

Asked in: CSAT 2021

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