Number of steps for knight to reach (n,0) on infinite chessboard.

Terms

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