584213domain: NAppears in sequencesa(n) = smallest semiprime s such that s + n is the next semiprime and there is no prime between s and s + n.at n=23A133478Lower ends of record gaps between numbers that are either primes or semiprimes.at n=12A275013Least number that is the start of a prime-semiprime gap of size n.at n=23A278351