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A363428 Squares whose base-3 expansion has no 0.

%I A363428 #17 Jun 19 2023 10:43:13
%S A363428 1,4,16,25,49,121,400,484,1444,1849,3364,5476,10201,10609,10816,12769,
%T A363428 17161,19321,19600,155236,169744,274576,286225,344569,346921,450241,
%U A363428 502681,863041,885481,984064,1042441,4008004,4190209,4596736,7203856,7263025,7706176,12752041,14326225,14341369,23833924
%N A363428 Squares whose base-3 expansion has no 0.
%H A363428 Chai Wah Wu, <a href="/A363428/b363428.txt">Table of n, a(n) for n = 1..3370</a> (terms 1..254 from Robert Israel)
%e A363428 a(5) = 49 is a term because 49 = 7^2 = 1121_3.
%p A363428 R1:= {1};
%p A363428 S1:= {1,2};
%p A363428 for i from 1 to 15 do
%p A363428   S1:= map(t -> (3*t+1, 3*t+2), S1);
%p A363428   R1:= R1 union select(issqr,S1);
%p A363428 od:
%p A363428 Rl;
%t A363428 Select[Range[5000]^2, ! MemberQ[IntegerDigits[#, 3], 0] &] (* _Amiram Eldar_, Jun 01 2023 *)
%o A363428 (Python)
%o A363428 from itertools import islice, count
%o A363428 from gmpy2 import digits
%o A363428 def A363428_gen(): # generator of terms
%o A363428     return filter(lambda n:'0' not in digits(n,3), (n**2 for n in count(0)))
%o A363428 A363428_list = list(islice(A363428_gen(),20)) # _Chai Wah Wu_, Jun 17 2023
%Y A363428 Intersection of A000290 and A032924. Cf. A363408.
%K A363428 nonn,base
%O A363428 1,2
%A A363428 _Robert Israel_, Jun 01 2023