Catalan Numbers
	=# ways to “parenthesize” (n+1) objects        Matrix Power Term   Graph (1((23)4))   A12A23A32A24A42A21 (((12)3)4)   A12A21A13A31A14A41 (1(2(34)))   A12A23A34A43A32A21 ((12)(34))   A12A21A13A34A43A31 ((1(23))4)   A12A23A32A21A14A41 = number of special paths on n departing from 1 once v Pass 1, (load=advance, multiply=retreat), Return to 1