Z-sequence for the Riordan triangle A111125.

Terms

a(0) =3a(1) =-4a(2) =12a(3) =-40a(4) =140a(5) =-504a(6) =1848a(7) =-6864a(8) =25740a(9) =-97240a(10) =369512a(11) =-1410864a(12) =5408312a(13) =-20801200a(14) =80233200a(15) =-310235040a(16) =1202160780a(17) =-4667212440a(18) =18150270600a(19) =-70690527600a(20) =275693057640