The Hwang-Deutsch function f_4(n).

Terms

a(0) =4a(1) =5a(2) =6a(3) =7a(4) =9a(5) =11a(6) =13a(7) =16a(8) =20a(9) =24a(10) =29a(11) =35a(12) =43a(13) =51a(14) =61a(15) =74a(16) =89a(17) =105a(18) =124a(19) =150a(20) =180a(21) =212a(22) =251a(23) =303a(24) =362a(25) =426a(26) =504a(27) =607a(28) =726a(29) =854