Well, you can try this code, but I don't know if it will work beyond n=9.
/* This program creates a half pyramid of nos. Created on 12.6.2k3. */
int n, i, r;
cout<<"Enter the number of numbers: ";
cout<<"\n This won't work out. ";
for (i=1; i<=n; i++)
for (r=1; r<=i; r++)
Enter the number of numbers: 7
btw, I didn't know it was called a pascal's triangle. I used to refer to it just as a no. pyramid or whatever.
First logic feature to see is that it is always symmetric about the central value in one sequence, so you will probably just need to store or compute one half of each row (from start to middle) and repeat in reverse for the remainder of the row (taking into account even and odd number of elements).
The second logic feature to see is more evident in the normal display of the pascal triangle (forgive the ASCII art):
From this it's clear that the operation that joins a \/ segment is the addition. So like in ganesh's pseudo-code, the basic idea is to add two adjacent elements of the previous row to get the corresponding element of the next row (except for the first element which is always 1 and the centre element of an odd-row which might be twice the element closest to centre of the even-row above it).
Show us some code of your own, and we can help you further.