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A308094 Arrange distinct numbers in a single square spiral so that the absolute difference between each number and its eight neighbors is unique. 0
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified September 16 23:53 EDT 2021. Contains 347477 sequences. (Running on oeis4.)