Two integer sequences are defined for n >= 1 by
a_n = 2 a_{n-1} + b_{n-1}
b_n = a_{n-1} + b_{n-1}
with a_0 = 1 and b_0 = 0.
Compute a_n modulo 998244353.
One line with the integer n.
a_n modulo 998244353.
0 <= n <= 10^18
This is a standard problem: a submission scores full points if it produces the correct output for every test case, and zero otherwise.
3
13
10
10946