Ulam's spiral (WNW spoke).

Terms

a(0) =1a(1) =18a(2) =67a(3) =148a(4) =261a(5) =406a(6) =583a(7) =792a(8) =1033a(9) =1306a(10) =1611a(11) =1948a(12) =2317a(13) =2718a(14) =3151a(15) =3616a(16) =4113a(17) =4642a(18) =5203a(19) =5796a(20) =6421a(21) =7078a(22) =7767a(23) =8488a(24) =9241a(25) =10026a(26) =10843a(27) =11692a(28) =12573a(29) =13486