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Smallest square containing exactly n 9's.
5

%I #12 Jul 27 2018 08:45:22

%S 9,3969,29929,1999396,299739969,2909199969,19299599929,909995799969,

%T 9499999990849,999999202999696,9969959993997969,90949999999997329,

%U 9199999971969929929,199999969997999200969,19997911999199999979409,295191999919994299999969

%N Smallest square containing exactly n 9's.

%C a(20) > 10^28. - _Giovanni Resta_, Jul 27 2018

%H Giovanni Resta, <a href="/A036516/b036516.txt">Table of n, a(n) for n = 1..19</a>

%t a[n_] := Block[{k=1}, While[DigitCount[k^2, 10, 9] != n, k++]; k^2]; Array[a, 6] (* _Giovanni Resta_, Jul 27 2018 *)

%Y Cf. A048354. - _Jon E. Schoenfield_, Jan 24 2009

%K nonn,base

%O 1,1

%A _David W. Wilson_

%E More terms from _Jon E. Schoenfield_, Jan 24 2009

%E a(16) from _Giovanni Resta_, Jul 27 2018