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%I #20 Jun 14 2016 04:20:04
%S 1,2,3,7,12,21,38,107,212,31488,70107,387288,95610729,446653271,
%T 3148717107,21081079479,648070211589107021
%N When squared gives number composed of digits {1,4,9}.
%C 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 Chris, <a href="http://rec-puzzles.org/index.php/Three%20Digits%20Solution">Three Digits Solution</a>, June 29, 2005.
%H 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 Patrick De Geest, <a href="http://www.worldofnumbers.com/square.htm">Palindromic Squares</a>
%H 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 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SquareNumber.html">Square Number.</a>
%e Since 107^2 = 11449, 107 is in the sequence.
%e As 108^2 = 11664 has two 6's, 108 is not in the sequence.
%t Select[Range[100], Complement[IntegerDigits[#^2], {1, 4, 9}] == {} &] (* _Alonso del Arte_, Jun 11 2016 *)
%Y Cf. A006716.
%K nonn,base,more
%O 1,2
%A _Patrick De Geest_
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