237522domain: NAppears in sequencesa(n) = Sum_{i=1..floor((n+2)/4)} a(2i-1)*a(n-2i+1), with a(1)=3, a(2)=1, and a(3)=2.at n=12A024963Squarefree numbers differing by more than 3 from any other squarefree number.at n=24A268332Tetraprime numbers differing by more than 3 from any other squarefree number.at n=3A369238