Your original question wasn't stupid or silly at all, because some people do need/want MIDI hardware sequencers that they can use on stage with other MIDI equipment. When I read your question, I actually thought you already had a MIDI hardware sound module or instrument that you wanted to connect a sequencer to, so I didn't think there was anything odd about your question; I must have missed the part where you mentioned connecting the sequencer to speakers, or else I missed the implications.
If you don't mind using your computer to do the sequencing, you can generally use just about any DAW for that. It's difficult to make a blanket statement about this, because some DAWs have a "built-in" arpeggiator effect available, while others don't but might let you use a third-party plugin for that. Some DAWs-- especially the free "lite" versions of certain commercial DAWs-- don't let you use any third-party plugins, or may limit you to specific types of plugins (VST, VST2, VST3, AU, etc.), so you need to look at your particular DAW's built-in features as well as its restrictions about third-party plugins.