2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/231229We provide some variations on the Greene-Krammer's identity which involve q-Catalan numbers. Our method reveals a curious analogy between these new identities and some congruences modulo a prime.CombinatoricsNumber Theory11B65, 11A07 (Primary) 05A10, 05A19 (Secondary)text