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%I #9 Feb 08 2022 17:58:06
%S 0,1,3,7,13,20,28,40,52,66,82,99,117,140,164,189,215,243,273,304,336,
%T 376,414,454
%N Minimum number of 1's in an n X n binary matrix with no zero 2 X 2 submatrix.
%F a(n) = A347472(n) + 1 = n^2 - A001197(n) + 1 = n^2 - A072567(n).
%F a(n) >= A152125(n).
%e Solutions for a(3)=3, a(4)=7, a(5)=13), a(6)=20:
%e . . x . . . x . . . . x . . . x x x
%e . x . . x x . . x x x . . x x . . x
%e x . . x . x . x . x x . x . x . x .
%e x x . . x x . x . x x . x . .
%e x x x . . . x x x x .
%e x . x x . x
%Y Column 2 of A339635.
%Y Cf. A001197, A072567, A152125, A227133, A347472.
%K nonn,more
%O 1,3
%A _Andrew Howroyd_, Dec 23 2021
%E a(22)-a(24) computed from A001197, added by _Max Alekseyev_, Feb 08 2022
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