100834domain: NAppears in sequencesLeast integers that satisfy sum(n>0,1/a(n)^z)=0, where a(1)=1, a(n+1)>a(n) and z=I.at n=9A084813Semiprime numbers that are sandwiched between products of exactly 4 distinct primes (or tetraprimes).at n=6A375964