A337368 - OEIS

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A337368

Spiral on a 2D square lattice, one term per cell, starting at the origin with 0; the four integers forming any 2 X 2 square have all digits 0 through 9 (with duplicate digits allowed).

0, 1, 2, 3456789, 3, 12, 4, 356789, 24, 5, 306789, 45, 6, 103789, 7, 102, 8, 45679, 80, 35679, 9, 1028, 10, 11, 306798, 13, 42, 14, 20, 13789, 15, 204, 25, 46, 3589, 467, 16, 20359, 17, 23, 41, 208, 18, 34567, 19, 34576, 289, 54, 21, 22, 4056789, 26, 305789, 36, 145, 206, 27, 3489, 67, 1389, 70, 112, 30

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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