Prime number spiral (clockwise, East spoke).

Terms

a(0) =2a(1) =7a(2) =47a(3) =139a(4) =283a(5) =503a(6) =797a(7) =1151a(8) =1579a(9) =2089a(10) =2689a(11) =3361a(12) =4099a(13) =4967a(14) =5861a(15) =6883a(16) =8011a(17) =9199a(18) =10457a(19) =11903a(20) =13313a(21) =14887a(22) =16547a(23) =18269a(24) =20161a(25) =22091a(26) =24083a(27) =26297a(28) =28573a(29) =30941