tokens: The authors thank J. Mauerhan for sharing his late-time spectra of SN 2013ej and S. Valenti for sharing his photometry of SN 2013by. CSB's research is supported in part by a Fellowship from Dartmouth’s School of Graduate and Advanced Studies. This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile. Archival observations of SNe were downloaded from the Open Supernova Catalog ( https://sne.space/ ).
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