login
A284486
The lexicographically earliest table read by antidiagonals such that any value appears at most twice on any straight line (of any slope).
2
1, 1, 1, 2, 1, 2, 2, 2, 3, 3, 3, 2, 3, 2, 4, 3, 4, 1, 1, 2, 3, 4, 3, 1, 3, 1, 4, 5, 4, 4, 2, 2, 3, 3, 5, 5, 5, 3, 5, 4, 2, 4, 6, 6, 7, 6, 5, 5, 6, 4, 7, 7, 4, 8, 2, 7, 5, 4, 5, 3, 6, 6, 7, 4, 8, 8, 6, 6, 8, 4, 7, 7, 8, 5, 5, 9, 3, 9, 8, 6, 6, 1, 8, 1, 9, 7, 3
OFFSET
1,4
COMMENTS
Conjecture: Every value appears twice on every line of rational slope that contains an infinite number of points.
EXAMPLE
Table begins:
A B C D E F
+---+---+---+---+---+---+
1 | 1 | 1 | 2 | 3 | 4 | 3 |
+---+---+---+---+---+---+
2 | 1 | 1 | 3 | 2 | 2 | |
+---+---+---+---+---+---+
3 | 2 | 2 | 3 | 1 | | |
+---+---+---+---+---+---+
4 | 2 | 2 | 1 | | | |
+---+---+---+---+---+---+
5 | 3 | 4 | | | | |
+---+---+---+---+---+---+
6 | 3 | | | | | |
+---+---+---+---+---+---+
a(17) = 4 (B5) because:
1 already appears twice on the line connecting B1-B2,
2 already appears twice on the line connecting B3-B4, and
3 already appears twice on the line connecting D1-C3.
CROSSREFS
Sequence in context: A207642 A053276 A064065 * A232194 A054705 A025800
KEYWORD
nonn,tabl,look
AUTHOR
Peter Kagey, Mar 27 2017
STATUS
approved