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A216191 Triangle T read by rows: T(n,k) equals the Manhattan distance between n and k when integers are arranged in a spiral. 0
0, 1, 0, 2, 1, 0, 1, 2, 1, 0, 2, 3, 2, 1, 0, 1, 2, 3, 2, 1, 0, 2, 3, 4, 3, 2, 1, 0, 1, 2, 3, 2, 3, 2, 1, 0, 2, 1, 2, 3, 4, 3, 2, 1, 0, 3, 2, 3, 4, 5, 4, 3, 2, 1, 0, 2, 1, 2, 3, 4, 3, 4, 3, 2, 1, 0, 3, 2, 1, 2, 3 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Spiral begins (0 at the center):

.

  42--43--44--45--46--47--48

   |

  41  20--21--22--23--24--25

   |   |                   |

  40  19   6---7---8---9  26

   |   |   |           |   |

  39  18   5   0---1  10  27

   |   |   |       |   |   |

  38  17   4---3---2  11  28

   |   |               |   |

  37  16--15--14--13--12  29

   |                       |

  36--35--34--33--32--31--30

LINKS

Table of n, a(n) for n=0..70.

FORMULA

T(n,n) = 0, T(n+1,n) = 1, T(n+2,n) = 2, T(n,k) <= n-k.

EXAMPLE

Triangle begins, 0 <= k <= n:

  0

  1, 0

  2, 1, 0

  1, 2, 1, 0

  2, 3, 2, 1, 0

  1, 2, 3, 2, 1, 0

  2, 3, 4, 3, 2, 1, 0

  1, 2, 3, 2, 3, 2, 1, 0

  2, 1, 2, 3, 4, 3, 2, 1, 0

  3, 2, 3, 4, 5, 4, 3, 2, 1, 0

  2, 1, 2, 3, 4, 3, 4, 3, 2, 1, 0

  3, 2, 1, 2, 3, 4, 5, 4, 3, 2, 1, 0

  4, 3, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1, 0

  3, 2, 1, 2, 3, 4, 5, 4, 3, 4, 3, 2, 1, 0

  2, 3, 2, 1, 2, 3, 4, 3, 4, 5, 4, 3, 2, 1, 0

  3, 4, 3, 2, 1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1, 0

CROSSREFS

Sequence in context: A106262 A025870 A104276 * A268834 A285914 A096875

Adjacent sequences:  A216188 A216189 A216190 * A216192 A216193 A216194

KEYWORD

nonn,tabl

AUTHOR

Philippe Deléham, Mar 11 2013

STATUS

approved

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Last modified July 19 12:35 EDT 2019. Contains 325159 sequences. (Running on oeis4.)