%I #17 Jun 19 2023 10:43:13

%S 1,4,16,25,49,121,400,484,1444,1849,3364,5476,10201,10609,10816,12769,

%T 17161,19321,19600,155236,169744,274576,286225,344569,346921,450241,

%U 502681,863041,885481,984064,1042441,4008004,4190209,4596736,7203856,7263025,7706176,12752041,14326225,14341369,23833924

%N Squares whose base-3 expansion has no 0.

%H 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 a(5) = 49 is a term because 49 = 7^2 = 1121_3.

%p R1:= {1};

%p S1:= {1,2};

%p for i from 1 to 15 do

%p S1:= map(t -> (3*t+1, 3*t+2), S1);

%p R1:= R1 union select(issqr,S1);

%p od:

%p Rl;

%t Select[Range[5000]^2, ! MemberQ[IntegerDigits[#, 3], 0] &] (* _Amiram Eldar_, Jun 01 2023 *)

%o (Python)

%o from itertools import islice, count

%o from gmpy2 import digits

%o def A363428_gen(): # generator of terms

%o return filter(lambda n:'0' not in digits(n,3), (n**2 for n in count(0)))

%o A363428_list = list(islice(A363428_gen(),20)) # _Chai Wah Wu_, Jun 17 2023

%Y Intersection of A000290 and A032924. Cf. A363408.

%K nonn,base

%O 1,2

%A _Robert Israel_, Jun 01 2023