A185586 EKG sequence (A064413) written clockwise as a square spiral and read counterclockwise.

2, 1, 6, 4, 18, 15, 5, 10, 8, 12, 9, 3, 24, 21, 7, 14, 36, 39, 13, 26, 28, 35, 25, 30, 27, 33, 11, 22, 20, 16, 38, 42, 51, 17, 34, 32, 58, 70, 65, 55, 60, 63, 49, 56, 54, 52, 50, 48, 69, 23, 46, 44, 40, 45, 57, 19, 64, 72, 93, 31, 62, 66, 87, 29, 141, 47, 94, 92, 100

Offset

1,1

Comments

A permutation of the natural numbers.

The subsequence of primes (A000040) begins: 2, 5, 3, 7, 13, 11, 17, 23, 19, 31, 29, 47, 43, 41, 37, 53, ...

Links

Alois P. Heinz, Table of n, a(n) for n = 1..10000

J. C. Lagarias, E. M. Rains and N. J. A. Sloane, The EKG sequence, arXiv:math/0204011 [math.NT], 2002.

J. C. Lagarias, E. M. Rains and N. J. A. Sloane, The EKG Sequence, Exper. Math. 11 (2002), 437-446.

I. Peterson, The EKG Sequence

Eric Weisstein's World of Mathematics, EKG Sequence

Index entries for sequences related to EKG sequence

Index entries for sequences that are permutations of the natural numbers

Example

1,2,4,6,3,9,12,8,10,5,15,18,... are written clockwise as a square spiral, then read counterclockwise: 2,1,6,4,18,15,5,10,8,12,9,3,...
The square spiral begins:
.
  33--27--30--25--35--28
   |                   |
  11  12---8--10---5  26
   |   |           |   |
  22   9   1---2  15  13
   |   |       |   |   |
  20   3---6---4  18  39
   |               |   |
  16--24--21---7--14  36
                       |
  38--42--51--17--34--32

Crossrefs

Cf. A064413.

Sequence in context: A268754 A357639 A005299 * A128728 A084950 A336382

Adjacent sequences: A185583 A185584 A185585 * A185587 A185588 A185589

Keyword

nonn,look

Author

Paul Curtz, Feb 04 2011

Status

approved