1496523600domain: NAppears in sequencesDenominator(sum(i=1,n,1/i^4))/denominator(sum(i=1,n,1/i^3)).at n=20A069047Denominator(sum(i=1,n,1/i^4))/denominator(sum(i=1,n,1/i^3)).at n=21A069047a(n) = (2n)!/(phi(2n)!)^2.at n=9A072116