区間ふるいを使ったらとけた。ひどいソース。 primes(Primes, Prime, NextPrimes) :- [Prime, _] = Primes, primes_next(Primes, NextPrimes). primes_next([Prime, [Head, Appender]], NextPrimes) :- P1 is Prime + 1, (primes_is_prime(P1, Head, Appende…