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 A027726 #14 Aug 11 2024 14:41:29
%S A027726 0,1,9,11,13,22,30,31,138,300,304,305,331,438,969,1141,1413,2367,3000,
%T A027726 3144,3881,9854,30000,30605,72062,106801,114141,125206,128348,300000,
%U A027726 315165,963304,980560,989154,2378507,3000000,3040604,3045679,3152290,3932806
%N A027726 Numbers k such that k^2+k+9 is a palindrome.
%H A027726 Giovanni Resta, <a href="/A027726/b027726.txt">Table of n, a(n) for n = 1..71</a>
%H A027726 P. De Geest, <a href="https://www.worldofnumbers.com/quasimor.htm">Palindromic Quasi_Over_Squares of the form n^2+(n+X)</a>
%t A027726 palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; f[n_] := n^2 + n + 9; Select[Range[0, 3*10^5], palQ@ f@ # &]
%Y A027726 Cf. A027727, A027694, A027757, A027758, A027724.
%K A027726 nonn,base
%O A027726 1,3
%A A027726 _Patrick De Geest_
%E A027726 More terms from _Giovanni Resta_, Aug 29 2018