尼科彻斯定理

Step 1 : Find the rule between output with n, found print n nums, and start = n * n - n + 1, and increase with common step

Step 2 : Coding and have a try.

#include <stdio.h>

int main()
{
    int n;
    while (scanf("%d", &n) != EOF) {
        int start = n * n - n + 1;
        printf("%d", start);
        int i;
        for (i = 1; i < n; i++) {
            printf("+%d", start + 2 * i);
        }
        
        printf("\n");
    }
    
    return 0;
}