The square G2\documentclass[12pt]{minimal}
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\begin{document}$$G^2$$\end{document} of a graph G\documentclass[12pt]{minimal}
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\begin{document}$$G$$\end{document} is defined on the vertex set V(G)\documentclass[12pt]{minimal}
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\begin{document}$$V(G)$$\end{document} of G\documentclass[12pt]{minimal}
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\begin{document}$$G$$\end{document} such that any two vertices with distance at most two in G\documentclass[12pt]{minimal}
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\begin{document}$$G$$\end{document} are linked by an edge. In this paper, the chromatic number and equitable chromatic number of the square S2(n,k)\documentclass[12pt]{minimal}
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\begin{document}$$S^2(n,k)$$\end{document} of Sierpiński graph S(n,k)\documentclass[12pt]{minimal}
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\begin{document}$$S(n,k)$$\end{document} are studied. It is obtained that χ(S2(n,k))=χ=(S2(n,k))=k+1\documentclass[12pt]{minimal}
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\begin{document}$$\chi (S^2(n,k))=\chi _{=}(S^2(n,k))=k+1$$\end{document} for n≥2\documentclass[12pt]{minimal}
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\begin{document}$$n\ge 2$$\end{document} and k≥2\documentclass[12pt]{minimal}
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\begin{document}$$k\ge 2$$\end{document}.
