|
| |
|
|
A014076
|
|
Odd nonprimes.
|
|
42
|
|
|
|
1, 9, 15, 21, 25, 27, 33, 35, 39, 45, 49, 51, 55, 57, 63, 65, 69, 75, 77, 81, 85, 87, 91, 93, 95, 99, 105, 111, 115, 117, 119, 121, 123, 125, 129, 133, 135, 141, 143, 145, 147, 153, 155, 159, 161, 165, 169, 171, 175, 177, 183, 185, 187, 189, 195, 201, 203, 205, 207
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
Same as A071904 except for the initial term 1 (which is not composite).
Numbers n such that product of first n odd numbers divided by sum of the first n odd numbers is an integer : 1*3*5*...*(2*n - 1) / (1 + 3 + 5 + ... + (2*n - 1)) = c. - Ctibor O. Zizka, Jun 26 2010
|
|
|
LINKS
|
_Reinhard Zumkeller_, Table of n, a(n) for n = 1..10000
|
|
|
FORMULA
|
A000035(a(n))*(1 - A010051(a(n)) = 1. - Reinhard Zumkeller, Sep 30 2011
|
|
|
MATHEMATICA
|
Select[Range@210, !PrimeQ@ # && OddQ@ # &] (* Robert G. Wilson v, Sep 22 2008 *)
Select[Range[1, 199, 2], PrimeOmega[#] != 1 &] (* Alonso del Arte, Nov 19 2012 *)
|
|
|
PROG
|
(Haskell)
a014076 n = a014076_list !! (n-1)
a014076_list = filter ((== 0) . a010051) a005408_list
-- Reinhard Zumkeller, Sep 30 2011
(PARI) is(n)=n%2 && !isprime(n) \\ Charles R Greathouse IV, Nov 24 2012
|
|
|
CROSSREFS
|
Cf. A002808, A005408; first differences: A067970, A196274; A047846.
Sequence in context: A160666 A039769 A071904 * A067800 A155474 A100819
Adjacent sequences: A014073 A014074 A014075 * A014077 A014078 A014079
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Warut Roonguthai
|
|
|
STATUS
|
approved
|
| |
|
|
