541840domain: NAppears in sequencesRefactorable numbers k such that 2*k + 1 is also a refactorable number.at n=7A281294Length of the long leg in the unique primitive Pythagorean triple (x,y,z) such that (x-y+z)/2 is A000032(n) and such that its long leg and its hypotenuse are consecutive natural numbers.at n=13A382379