A few new facts about the EKG sequence
Journal of integer sequences, Tome 11 (2008) no. 4
The EKG sequence is defined as follows: $a_1=1, a_2=2$ and $a_n$ is the smallest natural number satisfying $\gcd (a_{n-1}, a_n) > 1$ not already in the sequence. The sequence was previously investigated by Lagarias, Rains and Sloane. In particular, we know that $(a_n)$ is a permutation of the natural numbers and that the prime numbers appear in this sequence in an increasing order.
@article{JIS_2008__11_4_a2,
author = {Hofman, Piotr and Pilipczuk, Marcin},
title = {A few new facts about the {EKG} sequence},
journal = {Journal of integer sequences},
year = {2008},
volume = {11},
number = {4},
zbl = {1204.11057},
language = {en},
url = {http://geodesic.mathdoc.fr/item/JIS_2008__11_4_a2/}
}
Hofman, Piotr; Pilipczuk, Marcin. A few new facts about the EKG sequence. Journal of integer sequences, Tome 11 (2008) no. 4. http://geodesic.mathdoc.fr/item/JIS_2008__11_4_a2/