|
Search: id:A087086
|
|
|
| A087086 |
|
Primitive subsets of the integers 1 to n, each subset mapped onto a unique binary integer, values here shown in decimal. |
|
+0
2
|
|
| 0, 1, 2, 4, 6, 8, 12, 16, 18, 20, 22, 24, 28, 32, 40, 48, 56, 64, 66, 68, 70, 72, 76, 80, 82, 84, 86, 88, 92, 96, 104, 112, 120, 128, 132, 144, 148, 160, 176, 192, 196, 208, 212, 224, 240, 256, 258, 264, 272, 274, 280, 288, 296, 304, 312, 320, 322, 328, 336, 338, 344
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
COMMENT
|
A primitive set of integers has no pair of elements one of which divides the other. Each element i in a subset contributes 2^(i-1) to the binary value for that subset. The integers missing from the sequence correspond to nonprimitive subsets.
|
|
REFERENCES
|
Alan Sutcliffe, Divisors and Common Factors in Sets of Integers, awaiting publication
|
|
EXAMPLE
|
a(10)=22 since the 10th primitive set counting from 0 is (5,3,2), which maps onto 10110 binary = 22 decimal.
|
|
CROSSREFS
|
Cf. A051026 gives the number of primitive subsets of the integers 1 to n.
Adjacent sequences: A087083 A087084 A087085 this_sequence A087087 A087088 A087089
Sequence in context: A094109 A090404 A058825 this_sequence A103288 A125225 A092903
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 14 2003
|
|
|
Search completed in 0.002 seconds
|
