Sum up

发布时间: 2017年6月19日 00:24   时间限制: 1000ms   内存限制: 64M

One night, Kimi dreamed a really pleasing dream: he got in a room with piles of toys. And on the top of the toys is his favourite——"AutoDan". But the way of packing these toys was really special. "AutoDan" was on the top of the toys, and three toys consisted an triangle were on the second layer. The third layer has six toys which were also consisted an triangle, and so on. On the ith layer there was an triangle have i toys each edge(i*(i+1)/2 in total).And the whole heap seemed like a pyramid.

Kimi wants to know how many toys there are. It's up you to help Kimi to figure out the sum of all the toys.

The input will consist of some cases, each case takes a line with only one integer N(0<N<=100). It ends with a single 0.

You may output the sum in scientific notation in one line.

复制
1
3
0
1.00E0
1.00E1
when N=1 ,There is 1 toy.
when N=3 ,There is 1+3+6=10 toys.
1669

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