Does Panharmonicon double triggers from artifacts entering the battlefield as well as creatures?

Panharmonicon reads: 'If an artifact or creature entering the battlefield causes a triggered ability of an artifact or creature you control to trigger, that ability triggers an additional time.' This covers two distinct sources: artifacts entering and creatures entering — both are included in the same sentence.

The key rule here is CR 603.1, which governs triggered abilities (those beginning with 'when,' 'whenever,' or 'at'). Panharmonicon acts as a replacement-style doubling effect for those triggers specifically caused by artifacts or creatures entering the battlefield, provided the triggered ability belongs to an artifact or creature you control.

There are two separate conditions to satisfy: (1) the entering permanent must be an artifact or creature, and (2) the ability that triggers must be on an artifact or creature you control. Both must be true for Panharmonicon to apply. For example, a land entering would NOT trigger Panharmonicon's doubling effect.

Concrete example: You control Panharmonicon and play Solemn Simulacrum (an artifact creature). Its 'when Solemn Simulacrum enters the battlefield, you may search your library for a basic land' ability triggers — and because an artifact entered and the triggered ability is on an artifact you control, Panharmonicon doubles it, so you search for two basic lands instead of one.

Note that if a permanent is both an artifact and a creature, it still only triggers 'an additional time' once — Panharmonicon does not stack with itself for artifact creatures (CR 603.1, 603.2).