What rule does this pattern follow for 1203 1624 2045 2466?

The pattern in the given sequence is an arithmetic progression with a common difference of 421. Starting with 1203, each subsequent number is obtained by adding 421 to the previous number. Therefore, the rule followed by the pattern is: (n_{k+1} = n_k + 421), where (n_k) represents the k-th term in the sequence.