MathDB

SMT 2022 Discrete #6

Source:

April 1, 2023

Problem Statement

Let

\mathcal{A}

be the set of finite sequences of positive integers

a_1,a_2,\dots,a_k

such that

|a_n-a_{n-1}|=a_{n-2}

for all

3\leqslant n\leqslant k

. If

a_1=a_2=1

, and

k=18

, determine the number of elements of

\mathcal{A}