OFFSET
1,3
COMMENTS
This is the earliest permutation of the nonnegative integers with this property.
EXAMPLE
The spiral begins:
.
14--18--34--19--40--15
| |
25 4---5--12---8 43
| | | .
16 7 0---1 13 .
| | | | .
17 3---6---2 9
| |
11--21--31--22--10
.
The digits of the four integers inside each of the four 2 X 2 squares that contain the initial 0 add up to a square: 0 + 1 + 2 + 6 = 9, 0 + 6 + 3 + 7 = 16, 0 + 7 + 4 + 5 = 16, 0 + 5 + (1+2) + 1 = 9. This is true for any 2 X 2 square on the (infinite) grid; the upper right corner adds up to 25, for instance: (4+0) + (1+5) + 8 + (4+3) = 25; etc.
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, May 24 2022
STATUS
approved