#Java, 85 84 bytes
Java, 85 84 bytes
This is surprisingly short in Java.
void a(int a){String b="";for(int c=0;c++<a;System.out.println(b+=(c>1?" ":"")+c));}
Indented:
void a(int a){
String b="";
for(int c=0;
c++<a;
System.out.println(
b+=(c>1?" ":"")+c
));
}
1 byte thanks to Bigtoes/Geobits