A169849 EKG sequence started at 9 instead of 2.

9, 3, 6, 2, 4, 8, 10, 5, 15, 12, 14, 7, 21, 18, 16, 20, 22, 11, 33, 24, 26, 13, 39, 27, 30, 25, 35, 28, 32, 34, 17, 51, 36, 38, 19, 57, 42, 40, 44, 46, 23, 69, 45, 48, 50, 52, 54, 56, 49, 63, 60, 55, 65, 70, 58, 29, 87, 66, 62, 31, 93, 72, 64, 68, 74, 37, 111, 75, 78, 76, 80, 82, 41

Offset

1,1

Comments

A generalization of A064413.

a(n) = A064413(n+1) for n > 43; a(n) = A169837(n) for n > 9. - Reinhard Zumkeller, Jul 04 2014

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Gordon Hamilton, The EKG Sequence and the Tree of Numbers

Eric Weisstein's World of Mathematics, EKG Sequence

Index entries for sequences related to EKG sequence

Prog

(Haskell)
import Data.List (delete)
a169849 n = a169849_list !! (n-1)
a169849_list = 9 : ekg 9 (delete 9 [2..]) where
   ekg x zs = f zs where
       f (y:ys) = if gcd x y > 1 then y : ekg y (delete y zs) else f ys
-- Reinhard Zumkeller, Jul 04 2014

Crossrefs

Cf. A064413, A064417, A169837.

Sequence in context: A307960 A224235 A363716 * A182547 A019737 A088543

Adjacent sequences: A169846 A169847 A169848 * A169850 A169851 A169852

Keyword

nonn

Author

T. D. Noe and N. J. A. Sloane, Jun 02 2010

Status

approved