2795493855domain: NAppears in sequencesA four product triangle sequence based on :a=2;f(n,a)=f(n - 1, a) + a*f(n - 2, a).at n=23A174187A four product triangle sequence based on :a=2;f(n,a)=f(n - 1, a) + a*f(n - 2, a).at n=25A174187