Number of squares on infinite chessboard at <= n knight's moves from a fixed square.

Terms

a(0) =1a(1) =9a(2) =41a(3) =109a(4) =205a(5) =325a(6) =473a(7) =649a(8) =853a(9) =1085a(10) =1345a(11) =1633a(12) =1949a(13) =2293a(14) =2665a(15) =3065a(16) =3493a(17) =3949a(18) =4433a(19) =4945a(20) =5485a(21) =6053a(22) =6649a(23) =7273a(24) =7925a(25) =8605a(26) =9313a(27) =10049a(28) =10813a(29) =11605