Random number generator adds "-" for larger lengths (C programming)

I'm writing a function in C that generates a sequence of random integers given the length of the sequence. I've noticed that with numbers >66 the stdout shows "-" in between sets of numbers. How do I remove this and simply get a long string of integers? Here is my segment of code and the stdout: 1:

void gen_seq(int upper, int lower, int length) {
    srand((unsigned) time(NULL));
    char seq[length];
    int i, n;
    for (i = 0; i < length; i++) {
        n = (rand() % (upper - lower + 1)) + lower; // range of numbers to generate numbers from
        if (n != "-")
            seq[i] = n;
    }
    for (i = 0; i < length; i++)
        printf("%d", seq[i]);
    printf("\n");
}

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