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A087086 Primitive sets of integers, each subset mapped onto a unique binary integer, values here shown in decimal. 1
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; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

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

LINKS

Table of n, a(n) for n=0..60.

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.

Sequence in context: A090404 A015937 A058825 * A301587 A319796 A103288

Adjacent sequences:  A087083 A087084 A087085 * A087087 A087088 A087089

KEYWORD

easy,nonn,base

AUTHOR

Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 14 2003

STATUS

approved

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Last modified August 18 04:50 EDT 2019. Contains 326072 sequences. (Running on oeis4.)