Rodinol is a proprietary developer of Agfa-Gaevert origin, and as such I don't think that the formula has ever been officially released. However it's fairly widely understood that the developing agent is Para-aminophenol (probably Hydrochloride salt), activated by sodium hydroxide. It's about the only formulation that can give such a highly concentrated developer coupled with such high activity.(posted 8769 days ago)
I'll check, but I don't think the official Rodinol formula is published anywhere.