Kombinatorikos formulės

  1. Pn = 1∙2∙∙∙n = n!,     0! = 1
  2. Ank =
    n! / (n - m)!
  3. Amn = n(n - 1)∙∙∙(n - m + 1),     A0n = 1
  4. Am+1n = Pn = n!
  5. Am+1n = (n - m) Amn
  6. Cmn =
    n! / m!(n - m)!
    ,     n ≥ m
  7. Cmn =
    n(n - 1)∙∙∙(n - m + 1) / m!
    =
    n(n - 1)∙∙∙(n - m + 1) / 1∙2∙∙∙m
  8. Cmn + Cm+1n = Cm+1n+1,     0 ≤ m ≤ n