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 A201127 Maximum water retention of a semi-magic square of order n. 4
 4, 22, 78, 199, 424, 814, 1410 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 COMMENTS The same rules as for A201126 apply, but with the magic conditions for both diagonals of the number square removed. a(10) >= 2280. - Hugo Pfoertner, May 19 2012 LINKS Hugo Pfoertner, 3 X 3 Semi-magic square retaining 4 units of water Hugo Pfoertner, 4 X 4 Semi-magic square retaining 22 units of water Walter Trump, 5 X 5 Semi-magic square retaining 78 units of water Hugo Pfoertner, 6 X 6 Semi-magic square retaining 199 units of water Hugo Pfoertner, 7 X 7 Semi-magic square retaining 424 units of water Hugo Pfoertner, 8 X 8 Semi-magic square retaining 814 units of water Hugo Pfoertner, 9 X 9 Semi-magic square retaining 1410 units of water Wikipedia, Water retention on mathematical surfaces EXAMPLE (7 6 2) (5 1 9) (3 8 4) is a semi-magic square. The mid-side bricks with heights 6, 5, 9, 8 form a wall around the central hole with bottom height 1. Water poured upon the square will fill the central pond until overflowing via the left brick of height 5. Thus 4 units of water will be retained. CROSSREFS Cf. A201126 (water retention of magic squares). Sequence in context: A241689 A052149 A062966 * A259709 A078155 A237530 Adjacent sequences:  A201124 A201125 A201126 * A201128 A201129 A201130 KEYWORD nonn,hard,nice AUTHOR Hugo Pfoertner, Dec 03 2011 STATUS approved

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Last modified October 1 13:04 EDT 2020. Contains 337443 sequences. (Running on oeis4.)