A308094 Arrange distinct numbers in a single square spiral so that the absolute difference between each number and its eight neighbors is unique.

1, 2, 4, 8, 13, 21, 10, 31, 17, 34, 52, 26, 45, 68, 41, 66, 97, 131, 57, 96, 50, 139, 69, 114, 165, 83, 219, 107, 168, 102, 158, 221, 136, 198, 265, 166, 3, 237, 309, 386, 183, 261, 140, 349, 240, 319, 411, 270, 363, 179, 461, 322, 426, 279, 381, 488, 6, 364

Offset

1,2

Comments

Start with 1; always choose smallest number which has not yet appeared.

Links

Table of n, a(n) for n=1..58.

Example

The spiral begins:
.
   673--476--896--714--200--610--848--660--181--831--180
     |                                                 |
   877  125--280--513--393----9--336--481--364----6  658
     |    |                                       |    |
  1085  429    3--166--265--198--136--221--158  488  187
     |    |    |                             |    |    |
   770  554  237   97---66---41---68---45  102  381  647
     |    |    |    |                   |    |    |    |
   232    7  309  131   13----8----4   26  168  279   18
     |    |    |    |    |         |    |    |    |    |
   743  523  386   57   21    1----2   52  107  426  584
     |    |    |    |    |              |    |    |    |
   964   14  183   96   10---31---17---34  219  322   12
     |    |    |    |                        |    |    |
  1182  405  261   50--139---69--114--165---83  461  842
     |    |    |                                  |    |
   765  539  140--349--240--319--411--270--363--179  680
     |    |                                            |
   233    5--685--499---11--572---16--565---19--514---15

Crossrefs

Cf. A175498, A257339.

Sequence in context: A130840 A115266 A164508 * A292774 A026039 A004978

Adjacent sequences: A308091 A308092 A308093 * A308095 A308096 A308097

Keyword

nonn

Author

Luca Petrone, May 12 2019

Status

approved