No explicit loop, just recursion and repetition:

$p=1;sub p{my$x=shift;$x||exit;say" "x(3-$x),"*"x$x;$p=-1if$x>2;p($x+$
+p)}p 1
[download]

Update: Not so funny in C:

#include<stdio.h>
int p,n;void q(int x){int j;if(!x)return;for(j=1;j<=n-x;j++)printf(" "
+);for(j=1;j<=x;j++)printf("*");printf("\n");if(x>=n)p=-1;q(x+p);}void
+ main(){printf("Enter the number of columns: ");scanf("%d",&n);p=1;q(
+1);}
[download]

(I've never really used C, anyway.)