C++ :

#include<stdio.h>
int f(int n)
{
    if( n > 1 )
        n += f(n - 1);
    return n;
}
int main()
{
    int n;
    while(~scanf("%d",&n))
        printf("%d\n",f(n)+1);
    return 0;
}

Pascal :

var m:longint;
n,t:integer;
begin
readln(n);
m:=1; 
for t:=1 to n do 
m:=m+t; 
writeln(m); 
readln
end.