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

Terms

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