Equihash is a proof-of-work (PoW) algorithm that is designed to be resistant to the use of specialized ASICs. It is based on the concept of a "generalized birthday problem," and uses a computer's memory to perform the proof-of-work calculations. Equihash(125,4) is a variant of Equihash algorithm. It is a proof-of-work hash algorithm introduced by the University of Luxembourg research group CryptoLUX. Equihash is designed to tackle the problem of ASICs dominance in Bitcoin-like systems. This variant of the Equihash algorithm uses a parameter n = 125 and k = 4. It requires 4GB of memory to perform the proof-of-work calculations, and is designed to be mined with consumer-grade hardware such as GPUs. It is the most memory-efficient variant, but also the least secure. It requires less memory but it is more vulnerable to attacks from specialized hardware.