A068226 Neighbor in 2-1 direction of numbers arranged as clockwise spiral.

6, 1, 4, 5, 18, 19, 20, 7, 8, 9, 2, 3, 14, 15, 16, 17, 38, 39, 40, 41, 42, 21, 22, 23, 24, 25, 10, 11, 12, 13, 32, 33, 34, 35, 36, 37, 66, 67, 68, 69, 70, 71, 72, 43, 44, 45, 46, 47, 48, 49, 26, 27, 28, 29, 30, 31, 58, 59, 60, 61, 62, 63, 64, 65, 102, 103, 104, 105, 106, 107

Offset

1,1

Comments

Any offset (x,y) in this spiral is a permutation of the natural numbers.

Links

Peter Kagey, Table of n, a(n) for n = 1..10000

Frank Ellermann, Some EIS sequences based on a spiral of natural numbers.

Index entries for sequences that are permutations of the natural numbers.

Example

For example, if the spiral is oriented such that 1 is immediately to the left of 2, as shown below, then a(1) = 6 because 6 is immediately to the left of 1.
  21--22--23--24--25--26
  |                    |
  20  7---8---9---10  27
  |   |            |   |
  19  6   1---2   11  28
  |   |       |    |   |
  18  5---4---3   12  29
  |                |   |
  17--16--15--14--13  30
                       |
  36--35--34--33--32--31

Crossrefs

Cf. A068225 (inverse, right), A334751 (above), A334752 (below).

Sequence in context: A198565 A374838 A190409 * A011237 A195433 A358559

Adjacent sequences: A068223 A068224 A068225 * A068227 A068228 A068229

Keyword

nonn,easy

Author

Frank Ellermann, Feb 22 2002

Status

approved