80507domain: NAppears in sequencesNumber of regions in regular n-gon which are quadrilaterals (4-gons) when all its diagonals are drawn.at n=45A067151Numerator of h(n+6) - h(n), where h(n) = Sum_{k=1..n} 1/k.at n=14A192359a(n) = Sum_{d|n} sigma(d)^3.at n=19A344044Numbers k such that sigma(k) = psi(k) + tau(k)^3.at n=28A390297