3981264domain: NAppears in sequencesphi(n) plus the n-th prime gives a fourth power.at n=10A114084Number of ways to choose three points in an (n X n)-grid (or geoplane).at n=16A178208Quarter-square tetrahedrals: a(n) = k*(k - 1)*(k - 2)/6, k = A002620(n).at n=34A217482