How many positive integers $a$ with $a \le 154$ are there such that the coefficient of $x^a$ in the expansion of 
\[(1+x^{7}+x^{14}+ \cdots +x^{77})(1+x^{11}+x^{22}+\cdots +x^{77})\] 
is zero?

Let's think step by step and output the final answer within \boxed{}.
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