Number of binary codes of length 4 with n words.

Terms

a(0) =1a(1) =1a(2) =4a(3) =6a(4) =19a(5) =27a(6) =50a(7) =56a(8) =74a(9) =56a(10) =50a(11) =27a(12) =19a(13) =6a(14) =4a(15) =1a(16) =1