MathDB

2.4

Part of 2015 Saudi Arabia Pre-TST

Problems(1)

a_i \equiv i^2 mod 12 for all 1 <= i <= 11

Source: 2015 Saudi Arabia Pre-TST 2.4

9/12/2020
How many sequences of integers 1≤a1≤a2≤...≤a11≤20151 \le a_1 \le a_2\le ... \le a_{11 }\le 2015 that satisfy ai≡i2a_i \equiv i^2 (mod 1212) for all 1≤i≤111 \le i \le 11 are there?
(Le Anh Vinh)
number theory