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 A027675 #23 Feb 16 2025 08:32:35
%S A027675 1,2,3,7,12,21,38,107,212,31488,70107,387288,95610729,446653271,
%T A027675 3148717107,21081079479,648070211589107021
%N A027675 When squared gives number composed of digits {1,4,9}.
%C A027675 If a number has a least significant digit of 0, 4, 5 or 6, it can't be in this sequence. - _Alonso del Arte_, Jun 11 2016
%H A027675 Chris, <a href="http://rec-puzzles.org/index.php/Three%20Digits%20Solution">Three Digits Solution</a>, June 29, 2005.
%H A027675 Patrick De Geest, <a href="http://www.worldofnumbers.com/threedigits.htm">Squares containing at most three distinct digits, Index entries for related sequences</a>
%H A027675 Patrick De Geest, <a href="https://www.worldofnumbers.com/nobase10pg2.htm">Palindromic Squares in bases 2 to 17</a>
%H A027675 A. Ottens, <a href="http://einstein.et.tudelft.nl/~arlet/puzzles/sol.cgi/arithmetic/digits/squares/three.digits">The arithmetic-digits-squares-three.digits problem</a> [broken link].
%H A027675 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SquareNumber.html">Square Number.</a>
%e A027675 Since 107^2 = 11449, 107 is in the sequence.
%e A027675 As 108^2 = 11664 has two 6's, 108 is not in the sequence.
%t A027675 Select[Range[100], Complement[IntegerDigits[#^2], {1, 4, 9}] == {} &] (* _Alonso del Arte_, Jun 11 2016 *)
%Y A027675 Cf. A006716.
%K A027675 nonn,base,more
%O A027675 1,2
%A A027675 _Patrick De Geest_