hdu 2139 Calculate the formula

#include<stdio.h>__int64 num[100001];int main(){int i,n;num[1]=1;num[3]=10;for(i=5;i<=100001;i=i+2)num[i]=num[i-2]+i*i;while(scanf("%d",&n)!=EOF){printf("%I64d\n",num[n]);}return 0;}

#include<stdio.h>int main(){__int64 sum,n;while(scanf("%I64d",&n)!=EOF){sum=0;sum=n*(n+1)*(n+2)/6;printf("%I64d\n",sum);}return 0;}