9493504domain: NAppears in sequencesGeneralized class numbers c_(n,3).at n=6A000508Generalized Euler number c(7,n).at n=3A064068Main diagonal of A349271.at n=6A349263Generalized Euler numbers, a(n) = n!*[x^n](sec(7*x)*(-sin(2*x) + sin(4*x) + sin(6*x) + cos(x) + cos(3*x) - cos(5*x))).at n=6A349266