Se eu entendi bem, você precisa evitar index.html download.
Então você precisa disso (da página wget
man):
-R rejlist --reject rejlist
Specify comma-separated lists of file name suffixes or patterns to
accept or reject. Note that if any of the wildcard characters, *,
?, [ or ], appear in an element of acclist or rejlist, it will be
treated as a pattern, rather than a suffix. In this case, you have
to enclose the pattern into quotes to prevent your shell from
expanding it, like in -A "*.mp3" or -A '*.mp3'.
Portanto, você precisa adicionar -R index.html e instruirá wget
a excluir index.html da lista de arquivos para download.