|
Search: id:A057561
|
|
|
| A057561 |
|
A density problem involving linear forms.
(Formerly M0949)
|
|
+0
5
|
|
| 1, 2, 2, 3, 4, 5, 5, 6, 7, 7, 8, 8, 9, 10, 11, 11, 12, 13, 13, 14, 14, 15, 16, 17, 17, 18, 18, 19, 20, 20, 21, 22, 22, 23, 24, 25
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
A094708(n) = n - a(n)
Position of first n gives A004059(n).
Contribution from S. R. Finch (Steven.Finch(AT)inria.fr), Feb 27 2009: (Start)
Size of the largest set encompassing no {x, 2x, 3x} contained in D(n) = the first n 3-smooth numbers {1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 27,...} (A003586).
This is the weakly triple-free analog of A157271. (End)
|
|
REFERENCES
|
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
R. L. Graham et al., On extremal density theorems for linear forms, pp. 103-109 of H. Zassenhaus, editor, Number Theory and Algebra. Academic Press, NY, 1977.
|
|
LINKS
|
S. R. Finch, Triple-Free Sets of Integers
|
|
CROSSREFS
|
Cf. A004059, A094708.
Sequence in context: A065855 A034137 A156351 this_sequence A064726 A057359 A076538
Adjacent sequences: A057558 A057559 A057560 this_sequence A057562 A057563 A057564
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
N. J. A. Sloane (njas(AT)research.att.com).
|
|
EXTENSIONS
|
Edited by S. R. Finch (Steven.Finch(AT)inria.fr), Feb 25 2009
|
|
|
Search completed in 0.002 seconds
|
