Number of quaternary codes of length 2 with n words.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =13a(6) =23a(7) =26a(8) =32a(9) =26a(10) =23a(11) =13a(12) =10a(13) =4a(14) =2a(15) =1a(16) =1a(17) =0a(18) =0a(19) =0a(20) =0a(21) =0a(22) =0a(23) =0a(24) =0a(25) =0a(26) =0a(27) =0a(28) =0a(29) =0