题解 | #等差数列#
等差数列
http://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
int main(void) {
int n;
while(~scanf("%d", &n)) {
printf("%d\n", (2+2+3*(n-1))*n/2);
}
}
等差数列
http://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
int main(void) {
int n;
while(~scanf("%d", &n)) {
printf("%d\n", (2+2+3*(n-1))*n/2);
}
}
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