A036509 - OEIS

%I #18 Jul 27 2018 08:46:44

%S 25,225,22201,2002225,21022225,212722225,11222224225,132922222225,

%T 12222722202201,22222220262025,1222522204222225,22292262226224225,

%U 2222262262926922225,22226224222205212225,2222222222222640225,22222262422274682222225,1222212242622225512222224,2220022223125222222222201

%N Smallest square containing exactly n 2's.

%C a(21) > 10^28. - _Giovanni Resta_, Jul 27 2018

%H Giovanni Resta, <a href="/A036509/b036509.txt">Table of n, a(n) for n = 1..20</a>

%F a(n) = A048347(n)^2. - _Max Alekseyev_, Oct 20 2008

%t a[n_] := Block[{k=1}, While[DigitCount[k^2, 10, 2] != n, k++]; k^2]; Array[a, 7] (* _Giovanni Resta_, Jul 27 2018 *)

%Y Cf. A048347. - _Jon E. Schoenfield_, Jan 24 2009

%K nonn,base

%O 1,1

%A _David W. Wilson_

%E a(13)-a(15) from _Max Alekseyev_, Oct 20 2008, Nov 10 2008, Dec 05 2008

%E a(16)-a(18) from _Jon E. Schoenfield_, Dec 25 2008