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A185586
EKG sequence (A064413) written clockwise as a square spiral and read counterclockwise.
2
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
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
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
KEYWORD
nonn,look
AUTHOR
Paul Curtz, Feb 04 2011
STATUS
approved