A036509 Smallest square containing exactly n 2's.

25, 225, 22201, 2002225, 21022225, 212722225, 11222224225, 132922222225, 12222722202201, 22222220262025, 1222522204222225, 22292262226224225, 2222262262926922225, 22226224222205212225, 2222222222222640225, 22222262422274682222225, 1222212242622225512222224, 2220022223125222222222201

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base

Comments

a(21) > 10^28. - Giovanni Resta, Jul 27 2018

Links

• Giovanni Resta, Table of n, a(n) for n = 1..20

Crossrefs

Cf. A048347. - Jon E. Schoenfield, Jan 24 2009

Programs

Mathematica

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

Formula

a(n) = A048347(n)^2. - Max Alekseyev, Oct 20 2008

Extensions

a(13)-a(15) from Max Alekseyev, Oct 20 2008, Nov 10 2008, Dec 05 2008

a(16)-a(18) from Jon E. Schoenfield, Dec 25 2008