Abstract Consider a commutative ring $R$ with an identity element $1\neq0$. The set $Z(R)'$ is defined as the collection of all
elements in the ring $R$ that are non-zero and non units. The undirected graph ${\Gamma'(R)}$ with vertex set $Z(R)'$,
known as the cozero-divisor graph of $R$. In this graph, two distinct vertices, denoted by $x$ and $y$, are connected by an edge
if and only if $x$ is not an element of the ideal $yR$ and $y$ is not an element of the ideal $xR$. In this article,
we find the Laplacian eigenvalues of the graphs ${\Gamma'(\mathbb Z_n)}$ for $n=q_1^{Q}q_2q_3$ and $q_1^{Q_1}q_2^{Q_2}q_3$,
where $q_1,q_2,q_3$ are distinct primes and $Q, {Q_1},{Q_2}$ are positive integers. 
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