Minimum number of steps for a knight to reach (n,n) on an infinite chessboard.

Terms

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