Prime number spiral (clockwise, Southwest spoke).

Terms

a(0) =2a(1) =17a(2) =73a(3) =191a(4) =367a(5) =607a(6) =919a(7) =1297a(8) =1753a(9) =2309a(10) =2909a(11) =3623a(12) =4421a(13) =5303a(14) =6257a(15) =7307a(16) =8447a(17) =9643a(18) =10979a(19) =12421a(20) =13883a(21) =15467a(22) =17203a(23) =19037a(24) =20921a(25) =22853a(26) =24953a(27) =27091a(28) =29389a(29) =31859