Binomial coefficient C(18,n).

Terms

a(0) =1a(1) =18a(2) =153a(3) =816a(4) =3060a(5) =8568a(6) =18564a(7) =31824a(8) =43758a(9) =48620a(10) =43758a(11) =31824a(12) =18564a(13) =8568a(14) =3060a(15) =816a(16) =153a(17) =18a(18) =1