a(n) = (n+9)!/9!.A049398a(n) = (n+9)!/9!.Terms a(0) =1a(1) =10a(2) =110a(3) =1320a(4) =17160a(5) =240240a(6) =3603600a(7) =57657600a(8) =980179200a(9) =17643225600a(10) =335221286400External referencesoeis: A049398