Complex sentence: Many now-discovered formulae are known for b as an exponent of 2 or 3 and n is an exponent of 2 or it is some other factor-rich value but where several of the terms of vector A are zero.
Split into simpler sentences: Many now-discovered formulae are known for b as an exponent of 2 or 3 and n is an exponent of 2 or it is some other factor-rich value. For many now-known formulae, several of the terms of vector A are zero.