

A078779


Union of S, 2S and 4S, where S = odd squarefree numbers (A056911).


7



1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 19, 20, 21, 22, 23, 26, 28, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 46, 47, 51, 52, 53, 55, 57, 58, 59, 60, 61, 62, 65, 66, 67, 68, 69, 70, 71, 73, 74, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 89, 91, 92, 93, 94, 95, 97, 101
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OFFSET

1,2


COMMENTS

Numbers n such that the cyclic group Z_n is a DCIgroup.
Numbers n such that A008475(n) = A001414(n).
A193551(a(n)) = A000026(a(n)) = a(n).  Reinhard Zumkeller, Aug 27 2011
Union of squarefree numbers and twice the squarefree numbers (A005117).  Reinhard Zumkeller, Feb 11 2012
The complement is A046790.  Omar E. Pol, Jun 11 2016


LINKS

T. D. Noe, Table of n, a(n) for n = 1..7098
B. Alspach and M. Mishna, Enumeration of Cayley graphs and digraphs, Discr. Math., 256 (2002), 527539.
M. Mishna, Home Page
M. Muzychuk, On Adam's conjecture for circulant graphs, Discr. Math. 167 (1997), 497510.


FORMULA

a(n) = (Pi^2/7)*n + O(sqrt(n)).  Vladimir Shevelev, Jun 08 2016


PROG

(Haskell)
a078779 n = a078779_list !! (n1)
a078779_list = m a005117_list $ map (* 2) a005117_list where
m xs'@(x:xs) ys'@(y:ys)  x < y = x : m xs ys'
 x == y = x : m xs ys
 otherwise = y : m xs' ys
 Reinhard Zumkeller, Feb 11 2012, Aug 27 2011
(PARI) is(n)=issquarefree(n/gcd(n, 2)) \\ Charles R Greathouse IV, Nov 05 2017


CROSSREFS

Cf. A121176, A121684, A008475, A001414, A046790.
Sequence in context: A035060 A231272 A143719 * A047593 A181046 A032879
Adjacent sequences: A078776 A078777 A078778 * A078780 A078781 A078782


KEYWORD

nonn


AUTHOR

Benoit Cloitre, Jan 11 2003


EXTENSIONS

Edited by N. J. A. Sloane, Sep 13 2006


STATUS

approved



