153931domain: NAppears in sequencesNumerator of Sum_{k=1..n} k^4 / Product_{k=1..n} k^4.at n=28A181426Extra strong Lucas pseudoprimes.at n=17A217719The curvature (rounded down) of touching circles inscribed in a special way in the smaller segment of circle of radius 10/9 divided by a chord of length 4/3.at n=17A247512