20733domain: NAppears in sequencesNumbers k such that 51*2^k+1 is prime.at n=36A032375G.f.: Product_{m>0} 1/(1 - x^m + 2!*x^(2*m)).at n=38A293294Squarefree semiprimes k such that k+1 is the product of three distinct primes and k+2 is the product of four distinct primes.at n=24A376352