Prime number spiral (clockwise, South spoke).

Terms

a(0) =2a(1) =13a(2) =67a(3) =173a(4) =347a(5) =577a(6) =877a(7) =1249a(8) =1697a(9) =2243a(10) =2833a(11) =3541a(12) =4289a(13) =5179a(14) =6131a(15) =7159a(16) =8293a(17) =9473a(18) =10799a(19) =12251a(20) =13709a(21) =15289a(22) =16987a(23) =18749a(24) =20681a(25) =22619a(26) =24671a(27) =26839a(28) =29129a(29) =31541