2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/40291An explicit solution of time-homogeneous pure birth branching processes is described. It gives alternative extensions for the negative binomial distribution (branching processes with immigration) and for the Furry-Yule distribution (branching processes without immigration).6 pages, LATEX, sprocl.sty, to be published in Proc. of the ISMD2000, Tihany, Hungary. Editor corrections are includedHigh Energy Physics - Phenomenologytext