1=1
{{subst:subst}}Exp A/running |x=1 |n={{subst:expr}}1+1}} |term={{subst:expr}}1*1/{{{n}}}}} |sum=1+1 |value={{subst:expr}}1+1}} }}

Substituting this template produces one or more new substitution template calls, allowing recursive change of a page, see m:Help:Recursive conversion of wikitext.