a(n) = least positive integer > a(n-1) and not a(i)^2 + a(j)^2 for 1<=i<j<=n.

Terms

a(0) =2a(1) =3a(2) =4a(3) =5a(4) =6a(5) =7a(6) =8a(7) =9a(8) =10a(9) =11a(10) =12a(11) =14a(12) =15a(13) =16a(14) =17a(15) =18a(16) =19a(17) =21a(18) =22a(19) =23a(20) =24a(21) =26a(22) =27a(23) =28a(24) =30a(25) =31a(26) =32a(27) =33a(28) =35a(29) =36