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%I #22 Jun 13 2021 03:16:29
%S 1,2,5,8,11,17,21,28,35,42,51,60,69,80,91
%N Minimum number of cells in an n X n grid that need to be painted so that each unpainted cell is orthogonally adjacent to exactly two painted cells.
%H Dmitry Kamenetsky, <a href="/A344719/a344719.txt">Example solutions for n <= 11</a>.
%H Puzzling StackExchange, <a href="https://puzzling.stackexchange.com/questions/110250/paint-eleven-squares">Paint Eleven Squares</a>, 2021.
%Y Cf. A344301.
%K nonn,hard,more
%O 1,2
%A _Dmitry Kamenetsky_, May 28 2021
%E a(12)-a(15) from _Bert Dobbelaere_, Jun 13 2021