771079domain: NPropertiesPrimalityPrimeyesAppears in sequencesLargest prime dividing Sum_{k=0..n} k! * (n-k)!.at n=18A049413Numerators of b(n) = b(n-1)/2 + 1/(2*n), b(0)=0.at n=20A242376Prime numbersat n=61819