100401domain: NAppears in sequencesNumbers n such that s=n^2 gives prime quadruples (30s+11, 30s+13, 30s+17, 30s+19).at n=17A087772a(n) = Sum_{k=0..n} (-4)^k*binomial(n,k)^2*binomial(n-k,k)^2.at n=6A179524Number of (w,x,y,z) with all terms in {1,...,n} and w >= harmonic mean of {x,y,z}.at n=20A212107