a(n) = 1 + Sum_{k=0..n-6} binomial(n-5,k) * a(k).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =2a(7) =4a(8) =8a(9) =16a(10) =32a(11) =64a(12) =135a(13) =308a(14) =767a(15) =2059a(16) =5821a(17) =16963a(18) =50312a(19) =151189a(20) =460981a(21) =1433634a(22) =4578748a(23) =15110212a(24) =51704075a(25) =183423444a(26) =672385222a(27) =2534056116a(28) =9768179743a(29) =38357842713