cp's OEIS Frontend

A354373 Square spiral on a 2D square lattice, one term per cell, starting at the origin with 0; the digits of the four integers forming any 2 X 2 square add up to a prime.

%I A354373 #7 Jun 25 2022 22:04:07
%S A354373 0,1,2,4,3,6,5,8,11,7,9,10,12,14,15,13,16,18,23,21,17,25,27,19,22,20,
%T A354373 24,34,33,30,26,32,28,35,29,36,31,38,37,41,40,44,39,45,43,42,48,47,51,
%U A354373 46,49,53,55,59,60,57,50,66,75,64,54,58,62,71,52,73,79,82,84,80,56,88,61,93,68,65,67,91
%N A354373 Square spiral on a 2D square lattice, one term per cell, starting at the origin with 0; the digits of the four integers forming any 2 X 2 square add up to a prime.
%C A354373 This is the earliest permutation of the nonnegative integers with this property.
%e A354373 The spiral begins:
%e A354373 .
%e A354373      17--25--27--19--22--20
%e A354373       |                   |
%e A354373      21   5---8--11---7  24
%e A354373       |   |           |   .
%e A354373      23   6   0---1   9   .
%e A354373       |   |       |   |   .
%e A354373      18   3---4---2  10
%e A354373       |               |
%e A354373      16--13--15--14--12
%e A354373 .
%e A354373 The digits of the four integers inside each of the four 2 X 2 squares that contain the initial 0 add up to a prime: 0 + 1 + 2 + 4 = 7, 0 + 4 + 3 + 6 = 13, 0 + 6 + 5 + 8 = 19, 0 + 8 + (1+1) + 1 = 11. This is true for any 2 X 2 square on the (infinite) grid; the upper right corner adds up to 19, for instance: (2+2) + (2+0) + (2+4) + 7 = 19; etc.
%Y A354373 Cf. A337115, A337116, A337117, A337368, A354372.
%K A354373 base,nonn
%O A354373 1,3
%A A354373 _Eric Angelini_ and _Carole Dubois_, May 24 2022