546560domain: NAppears in sequencesa(n) = Sum_{k=1..n-1} k^5*sigma(k)*sigma(n-k).at n=7A259693Sheffer triangle S2[4,1] = (exp(x), exp(4*x) - 1).at n=24A285061E.g.f. C(x,y) = cos(y) / sqrt(1 - sin(x)^2 - sin(y)^2).at n=25A324609E.g.f. C(y,x) = cos(x) / sqrt(1 - sin(x)^2 - sin(y)^2).at n=23A324611