a(n) = binomial(n, round(sqrt(n))).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =10a(6) =15a(7) =35a(8) =56a(9) =84a(10) =120a(11) =165a(12) =220a(13) =715a(14) =1001a(15) =1365a(16) =1820a(17) =2380a(18) =3060a(19) =3876a(20) =4845a(21) =20349a(22) =26334a(23) =33649a(24) =42504a(25) =53130a(26) =65780a(27) =80730a(28) =98280a(29) =118755