Ulam's spiral (ESE spoke).

Terms

a(0) =1a(1) =10a(2) =51a(3) =124a(4) =229a(5) =366a(6) =535a(7) =736a(8) =969a(9) =1234a(10) =1531a(11) =1860a(12) =2221a(13) =2614a(14) =3039a(15) =3496a(16) =3985a(17) =4506a(18) =5059a(19) =5644a(20) =6261a(21) =6910a(22) =7591a(23) =8304a(24) =9049a(25) =9826a(26) =10635a(27) =11476a(28) =12349a(29) =13254