a(n) is the odd member of {x,y}, where x^2 + y^2 is the n-th prime of the form 4i+1.

Terms

a(0) =1a(1) =3a(2) =1a(3) =5a(4) =1a(5) =5a(6) =7a(7) =5a(8) =3a(9) =5a(10) =9a(11) =1a(12) =3a(13) =7a(14) =11a(15) =7a(16) =11a(17) =13a(18) =9a(19) =7a(20) =1a(21) =15a(22) =13a(23) =15a(24) =1a(25) =13a(26) =9a(27) =5a(28) =17a(29) =13