a(n) = Sum_{k=0..9} binomial(18,k)*binomial(n,k).

Terms

a(0) =1a(1) =19a(2) =190a(3) =1330a(4) =7315a(5) =33649a(6) =134596a(7) =480700a(8) =1562275a(9) =4686825a(10) =13079352a(11) =34084128a(12) =83204745a(13) =191006115a(14) =414237570a(15) =852920310a(16) =1675575165a(17) =3155247975a(18) =5719519850a(19) =10018268150a(20) =17013571223a(21) =28096825757a(22) =45238870040a(23) =71179679480a(24) =109665022415