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 A018849 #9 Aug 04 2014 06:14:28
%S A018849 0,1,121,6889,10201,69169,1002001,5221225,100020001,109181601,
%T A018849 522808225,602555209,10000200001,62188888129,1000002000001,
%U A018849 1212225222121,100000020000001,10000000200000001,10022212521222001,12102202520220121
%N A018849 Strobogrammatic squares: the same upside down (calculator-style numerals).
%C A018849 Subsequence of squares in A018846. - _Michel Marcus_, Aug 04 2014
%o A018849 (PARI) is_A018846(n, t=Vec("012..59.86"))={ apply(x->t[eval(x)+1], n=Vec(Str(n)))==vecextract(n, "-1..1"); }
%o A018849 lista(nn) = {for(n=0, nn, if (is_A018846(n^2), print1(n^2, ", ")));} \\ _Michel Marcus_, Aug 04 2014
%K A018849 nonn,base
%O A018849 1,3
%A A018849 _David W. Wilson_