Column l=4 of irregular triangle in A133709.

Terms

a(0) =0a(1) =0a(2) =140a(3) =1435a(4) =7693a(5) =30450a(6) =100330a(7) =291265a(8) =769015a(9) =1883436a(10) =4336320a(11) =9475195a(12) =19790605a(13) =39733150a(14) =77020830a(15) =144681850a(16) =264178990a(17) =470096240a(18) =817045500a(19) =1389681375a(20) =2317008105a(21) =3792539410a(22) =6102347050a(23) =9663627675a(24) =15077153821a(25) =23197881100