Remarks on a representation and isomorphisms of the multiple Riordan group

We consider presentation of a multiple Riordan array in the form of [Formula: see text] tuple ‘single’ Riordan arrays, which was recently proposed by Petrullo. We give an explicit formula for an isomorphism between the [Formula: see text]-tuple Riordan group [Formula: see text] and the subgroup of [Formula: see text].