OFFSET
0,3
COMMENTS
We consider an infinite chessboard on N^3 (the first octant of Z^3) traversed by increasing x+y+z and then increasing x+y and then increasing x and place nonattacking queens as soon as possible; these queens can attack along the 13 axes of rotation of a cube.
This sequence is a 3-dimensional variant of A275901.
LINKS
Rémy Sigrist, Table of n, a(n) for n = 0..10000
Rémy Sigrist, PARI program for A326757
Rémy Sigrist, Interactive scatterplot of the first 25000 queens
EXAMPLE
The traversal of N^3 starts:
X Y Z
- - -
0 0 0
0 0 1
0 1 0
1 0 0
0 0 2
0 1 1
1 0 1
0 2 0
1 1 0
2 0 0
0 0 3
0 1 2
1 0 2
...
The first queen is placed at position (0, 0, 0) and attacks every position (m*i, m*j, m*k) with max(i, j, k) = 1 and m > 0.
The second queen is placed at position (0, 1, 2).
PROG
(PARI) See Links section.
CROSSREFS
KEYWORD
nonn
AUTHOR
Rémy Sigrist and N. J. A. Sloane, Jul 23 2019
STATUS
approved