C(n-3,3)+C(n-7,7)+...+C(n-(4*floor((n-4)/4)+3),4*floor((n-4)/4)+3).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =1a(7) =4a(8) =10a(9) =20a(10) =35a(11) =56a(12) =84a(13) =120a(14) =166a(15) =228a(16) =322a(17) =484a(18) =785a(19) =1352a(20) =2396a(21) =4248a(22) =7405a(23) =12592a(24) =20856a(25) =33728a(26) =53524a(27) =83912a(28) =130956a(29) =204968