Or on a
donc
partant
or, posant n = 1 , N 2 N 1 = p r ; {\displaystyle n=1,\ \sideset {_{2}}{_{1}}{\mathrm {N} }={\frac {p}{r}}\,;} donc
Ensuite
or, posant n = 1 , N 3 N 1 = p 2 r 2 ; {\displaystyle n=1,\ \sideset {_{3}}{_{1}}{\mathrm {N} }={\frac {p^{2}}{r^{2}}}\,;} donc
et généralement
On a ensuite
partant,
or, posant n = 1 , M 2 M n = 1 − p r ; {\displaystyle n=1,\ \sideset {_{2}}{_{n}}{\mathrm {M} }={\frac {1-p}{r}}\,;} donc
et