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%I #16 Jul 03 2023 08:01:54
%S 0,100,102400,10000,10240000,1000000,1024000000,100000000,
%T 102400000000,10000000000,10240000000000,1000000000000,
%U 1024000000000000,100000000000000,102400000000000000,10000000000000000
%N Smallest square containing exactly n decimal digits '0'.
%F a(2*n) = 10^(2*n), a(2*n+1) = 1024*10^(2*n) for k >= 1 since 1024 is the smallest square factor that contains a single '0'. - _Georg Fischer_, Jul 03 2023
%t nsmall = Table[Infinity, 20];
%t For[i = 0, i <= 4*10^6, i++, n0 = Count[IntegerDigits[i^2], 0];
%t If[nsmall[[n0]] > i^2, nsmall[[n0]] = i^2]];
%t ReplaceAll[nsmall, Infinity -> "?"] (* _Robert Price_, Mar 22 2020 *)
%Y Cf. A036508 (digits 1), A036509 (2), A036510 (3), A036511 (4), A036512 (5), A036513 (6), A036514 (7), A036515 (8), A036516 (9).
%K nonn,base
%O 1,2
%A _David W. Wilson_
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