52975108096domain: NAppears in sequencesGeneralized Euler numbers c(4,n).at n=5A000490Shanks's array c_{a,n} (a >= 1, n >= 0) that generalizes Euler and class numbers, read by antidiagonals upwards.at n=41A235605Generalized Euler numbers, a(n) = n!*[x^n](sec(4*x)*(sin(4*x) + 1)).at n=10A349264