A subdiagonal of number array A082137.

Terms

a(0) =1a(1) =5a(2) =42a(3) =336a(4) =2640a(5) =20592a(6) =160160a(7) =1244672a(8) =9674496a(9) =75246080a(10) =585761792a(11) =4564377600a(12) =35602145280a(13) =277970595840