mekso variable arity (at most ternary) operator: number of prime divisors of number A, counting with or without multiplicity according to the value B (1 or 0 respectively), in structure C

A may be a number in a generalized sense: anything living in a ring with primes. Units are not considered to be prime factors. B toggles the type of counting: If B=0, then the prime factors are counted without multiplicity (they are counted only uniquely, ignoring their exponents); if B=1, then multiple factors of the same prime are counted (the exponents of the prime factors are added together); no other option for the value of B is currently defined; B might have contextual/cultural/conventional defaults but the contextless default value is B=1. C specifies in which (algebraic) structure primehood/factoring is being considered/performed; it need not be specified if the context is clear.