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%I #12 Jul 27 2018 08:46:56
%S 4,144,1444,44944,6441444,47444544,4434494464,44424414441,
%T 4243443441444,44844344414464,444431244445444,44044624434444544,
%U 441544444344443449,14444545446449449444,346454444084444444644,44024844440444424044544,444448493447444044441744
%N Smallest square containing exactly n 4's.
%C a(21) > 10^28. - _Giovanni Resta_, Jul 27 2018
%H Giovanni Resta, <a href="/A036511/b036511.txt">Table of n, a(n) for n = 1..20</a>
%t a[n_] := Block[{k=1}, While[DigitCount[k^2, 10, 4] != n, k++]; k^2]; Array[a, 7] (* _Giovanni Resta_, Jul 27 2018 *)
%Y Cf. A048349. - _Jon E. Schoenfield_, Jan 24 2009
%K nonn,base
%O 1,1
%A _David W. Wilson_
%E a(13)-a(16) from _Jon E. Schoenfield_, Jan 17 2009
%E a(17) from _Giovanni Resta_, Jul 27 2018