View Compilation Error

0_0_17265864_29206.c: In function 'main':
0_0_17265864_29206.c:1:44: error: called object 'a' is not a function or function pointer
 main(a){while(scanf("%d",&a)+1)printf("%d",a(a+1)/2);}
                                            ^
0_0_17265864_29206.c:1:1: note: declared here
 main(a){while(scanf("%d",&a)+1)printf("%d",a(a+1)/2);}
 ^