527520domain: NAppears in sequencesExpansion of Eisenstein series E_4(q) (alternate convention E_2(q)); theta series of E_8 lattice.at n=13A004009Array read by downward antidiagonals: A(n,k) = A(n-1,k+1) + 2*(k+1)!*Sum_{j=0..k} A(n-1,j)/j! with A(0,k) = 2*(k+1)!, n >= 0, k >= 0.at n=24A379459