n-sum 若剩余值

modulo-N sum N模数和

Riemann n sum 黎曼和

in n sum 总而言之

pollen n sum 花粉统计

sum to n terms 项和

n term sum n项和数

sum to n terms n 项和

n-person zero-sum game n人零和对策

n-person general sum game n人一般和对策