OFFSET
1,3
COMMENTS
This is defined to be the lexicographically earliest permutation of the nonnegative integers with this property.
LINKS
Jean-Marc Falcoz, Table of n, a(n) for n = 1..3907
EXAMPLE
The spiral starts with the 2 X 2 square 0,1,2,A and this square contains all the digits 0 through 9 at least once; the upper right 2 X 2 square (here) has the same property —— and so have all the 2 X 2 squares of the grid.
.
18———K——19———L——289—54———21——22 A = 3456789
| | B = 356789
208 9———G——10——11———H———13 4056789 C = 306789
| | | | D = 103789
41 F 4———B——24———5 42 26 E = 45679
| | | | | | F = 35679
23 80 12 0———1 C 14 305789 G = 1028
| | | | | | | H = 306798
17 E 3———A———2 45 20 36 I = 3589
| | | | . J = 20359
J 8——102——7———D———6 13789 . K = 34567
| | . L= 34576
16——467——I——46——25——204——15 . ...
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Jean-Marc Falcoz, Aug 25 2020
STATUS
approved