Question 69
The numbers $1, 8, 4, 0$ are the first four terms of the infinite sequence. Every subsequent term of the sequence is obtained as the last digit of the sum of previous four terms. Therefore the fifth term of the sequence is $3$, because $1+8+4+0=13$; the sixth term is $5$ because $8+4+0+3=15$, and so on.
a. Will $2, 0, 0, 7$ ever appear as a subsequence?
b. Will $1, 8, 4, 0$ appear again as a subsequence?
Explain your answer!
a. Will $2, 0, 0, 7$ ever appear as a subsequence?
b. Will $1, 8, 4, 0$ appear again as a subsequence?
Explain your answer!