9110640domain: NAppears in sequencesNumbers that can be expressed as the difference of the squares of primes in exactly twenty-four distinct ways.at n=4A092020a(n) = denominator of sum{k=1 to n} 1/A127515(k).at n=17A127517a(n) = denominator of sum{k=1 to n} 1/A127515(k).at n=18A127517