The sequence can be verified correct by a multicore computer in much less time than it took to generate it because the verifier can split up the sequence of hashes and their indexes to verify them in parallel. To generate the hashes, they had to be computed sequentially as they build off of each other but the verification process can simply cross-reference data in parallel and take only as long as the equation (total number of hashes)/(Hashes per second per core * Number of cores available to verify). Considering modern GPUs have hundreds or thousands of cores, the time consumption becomes increasingly small to verify.