Triangle T(n,k) represents the coefficients of (x^18*d/dx)^n, where n=1,2,3,....

Terms

a(0) =1a(1) =18a(2) =1a(3) =630a(4) =54a(5) =1a(6) =32760a(7) =3492a(8) =108a(9) =1a(10) =2260440a(11) =277200a(12) =11160a(13) =180a(14) =1a(15) =194397840a(16) =26376840a(17) =1259280a(18) =27180a(19) =270a(20) =1a(21) =20022977520a(22) =2937589200a(23) =158601240a(24) =4140360a(25) =56070a(26) =378a(27) =1a(29) =375471270720a(30) =22286940480