OFFSET
2,1
COMMENTS
Start with an n X n square grid. Each cell has neighbors horizontally and vertically. Place the numbers 1 and 2 anywhere. Now place the numbers 3, 4, ..., m in order, subject to the rule that when you place k, the sum of the numbers that a Chess Rook attack in the same row and column must equal k. Then a(n) is the maximum m that can be achieved.
LINKS
Rodolfo Kurchan, Puzzle Fun, Problems, Forest of Numbers
EXAMPLE
Solution for a(5) = 12 from Rodolfo Kurchan:
+---+---+---+---+---+
| 1 | | | 4 | 3 |
+---+---+---+---+---+
| 6 | | | | 5 |
+---+---+---+---+---+
| | | | 11| 7 |
+---+---+---+---+---+
| | | | | 9 |
+---+---+---+---+---+
| 8 | 10| 12| | 2 |
+---+---+---+---+---+
Solutions for a(2) to a(6) from Rodolfo Kurchan.
Solutions for a(7) to a(10) from Giorgio Vecchi.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Rodolfo Kurchan, Apr 23 2022
STATUS
approved