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 A027727 #16 Nov 21 2024 14:29:47
%S A027727 9,11,99,141,191,515,939,1001,19191,90309,92729,93339,109901,192291,
%T A027727 939939,1303031,1997991,5605065,9003009,9887889,15066051,97111179,
%U A027727 900030009,936696639,5193003915,11406560411,13028282031,15676667651,16473337461,90000300009
%N A027727 Palindromes of form k^2 + k + 9.
%C A027727 Palindromes h such that 4*h - 35 is a square. - _Bruno Berselli_, Aug 29 2018
%H A027727 Giovanni Resta, <a href="/A027727/b027727.txt">Table of n, a(n) for n = 1..71</a>
%H A027727 P. De Geest, <a href="https://www.worldofnumbers.com/quasimor.htm">Palindromic Quasi_Over_Squares of the form n^2+(n+X)</a>
%t A027727 palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; f[n_] := n^2 + n + 9; Select[f@ Range[0, 10^5], palQ] (* _Giovanni Resta_, Aug 29 2018 *)
%t A027727 Select[Table[k^2+k+9,{k,0,300000}],PalindromeQ] (* _Harvey P. Dale_, Nov 21 2024 *)
%Y A027727 Cf. A027726, A027694, A027757, A027758, A027725.
%K A027727 nonn,base
%O A027727 1,1
%A A027727 _Patrick De Geest_
%E A027727 More terms from _Giovanni Resta_, Aug 29 2018