This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A271186 #16 Aug 14 2022 06:53:30
%S A271186 1,9,17,25,49,73,81,89,97,121
%N A271186 Odd integers k such that k^k + 1 is the sum of 2 nonzero squares.
%e A271186 9 is a term because 9^9 + 1 = 1457^2 + 19629^2.
%t A271186 Select[Range[1, 25, 2], Length[PowersRepresentations[#^# + 1, 2, 2] /. {0, _} -> Nothing] > 0 &] (* _Michael De Vlieger_, Apr 01 2016 *)
%o A271186 (PARI) a014566(n) = n^n+1;
%o A271186 isA000404(n) = { for( i=1, #n=factor(n)~%4, n[1, i]==3 && n[2, i]%2 && return); n && ( vecmin(n[1, ])==1 || (n[1, 1]==2 && n[2, 1]%2))}
%o A271186 for(n=1, 1e2, if(isA000404(a014566(n)) && n%2 == 1, print1(n, ", ")));
%Y A271186 Cf. A000404, A014566.
%K A271186 nonn,more
%O A271186 1,2
%A A271186 _Altug Alkan_, Apr 01 2016
%E A271186 a(6)-a(10) from _Jinyuan Wang_, Aug 14 2022