Smallest prime in n-th shell of prime spiral.

Terms

a(0) =2a(1) =3a(2) =29a(3) =101a(4) =229a(5) =421a(6) =673a(7) =1013a(8) =1429a(9) =1889a(10) =2441a(11) =3089a(12) =3821a(13) =4639a(14) =5521a(15) =6491a(16) =7577a(17) =8741a(18) =9941a(19) =11329a(20) =12757a(21) =14341a(22) =15881a(23) =17623a(24) =19477a(25) =21397a(26) =23333a(27) =25471a(28) =27743a(29) =30059