(Note: This question has been cross-posted to MO.)
Can an odd perfect number be a nontrivial multiple of a triangular number?
(Note: This question has been cross-posted to MO.)
Can an odd perfect number be a nontrivial multiple of a triangular number?
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The answer turns out to be YES.
Claim
Proof
By Slowak's 1999 result, every odd perfect number must have the form $$\dfrac{{q^k}\sigma(q^k)}{2}\cdot{d'}$$ for some integer $d' > 1$.
If $k=1$, then our claim readily follows from Slowak's result.
Otherwise, if $k>1$, since $q \mid q^k$ and $(q + 1) \mid \sigma(q^k)$ for all $k \equiv 1 \pmod 4$, then we have that every odd perfect number must have the form $$\dfrac{q(q+1)}{2}\cdot{d''}$$ for some integer $d'' = ({q^{k-1}}{\sigma(q^k)}{d'})/(q+1) > 1$.