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A331543 Squares using only decimal digits 0,1,2,3.

%I A331543 #9 Jan 20 2020 09:16:36
%S A331543 0,1,100,121,10000,10201,12100,12321,22201,123201,130321,1000000,
%T A331543 1002001,1020100,1022121,1210000,1212201,1232100,1320201,2220100,
%U A331543 3101121,12320100,13032100,100000000,100020001,100200100,100220121,102010000,102030201,102212100,102232321,103002201,121000000,121022001,121220100
%N A331543 Squares using only decimal digits 0,1,2,3.
%C A331543 If n is a member then so is 100*n.
%C A331543 All terms == 0, 1, 100, 121, 201 or 321 (mod 1000).
%H A331543 Robert Israel, <a href="/A331543/b331543.txt">Table of n, a(n) for n = 1..400</a>
%e A331543 a(3) = 100 is a member because 100 = 10^2 and 100 has no digits > 3.
%p A331543 Res:= NULL: count:= 0:
%p A331543 for k from 0 while count < 50 do
%p A331543   for j in [0,1,100,121,201,321] do
%p A331543     L:= convert(k,base,4);
%p A331543     x:= add(L[i]*10^(i-1),i=1..nops(L))*1000+j;
%p A331543     if issqr(x) then count:= count+1; Res:= Res, x fi
%p A331543 od od:
%p A331543 Res;
%Y A331543 Cf. A030174.
%K A331543 nonn,base
%O A331543 1,3
%A A331543 _Robert Israel_, Jan 19 2020