You can remove all non primes in the selector, like below

span:nth-child(2n+4), span:nth-child(3n+6), span:nth-child(5n+10), span:nth-child(7n+14), span:nth-child(11n+22), span:nth-child(13n+26), span:nth-child(17n+34), span:nth-child(19n+38), span:nth-child(23n+46), span:nth-child(29n+58), span:nth-child(31n+62),