Binomial coefficient binomial(n,4) = n*(n-1)*(n-2)*(n-3)/24.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =5a(6) =15a(7) =35a(8) =70a(9) =126a(10) =210a(11) =330a(12) =495a(13) =715a(14) =1001a(15) =1365a(16) =1820a(17) =2380a(18) =3060a(19) =3876a(20) =4845a(21) =5985a(22) =7315a(23) =8855a(24) =10626a(25) =12650a(26) =14950a(27) =17550a(28) =20475a(29) =23751