Notation of symmetric sum notation When you use the symmetric sum notation, for example, $$\sum_\text{sym}abc+a$$ if there are 3 variables, then does abc count once, 3 times or 6 times?
I am confused about repetitions of the same expression in a symmetric sum notation.

We have that
$$\sum_\mathrm{sym}Q(x_i)=\sum_\sigma Q(x_{\sigma(i)})$$
for all permutations of $1, \ldots , n$. 
Therefore it should be
$$\sum_\text{sym}abc+a=Q(a,b,c)+Q(a,c,b)+Q(b,a,c)+Q(b,c,a)+Q(c,a,b)+Q(c,b,a)=$$
$$=2abc+2a+2abc+2b+2abc+2c=6abc+2(a+b+c)$$
