

A227956


Possible lengths of minimal prime number rulers.


0



3, 4, 6, 8, 12, 14, 18, 20, 24, 30, 32, 38, 44, 62
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OFFSET

1,1


COMMENTS

A ruler is a prime number ruler provided all its interior marks are on a prime number position. A ruler is called complete when any positive integer distance up to the length of the ruler can be measured. A complete ruler is called minimal when any subsequence of its marks is not complete for the same length. A complete ruler is perfect, if there is no complete ruler with the same length which possesses fewer marks. A perfect ruler is minimal (but not conversely). For definitions, references and links related to complete rulers see A103294.
The possible lengths of perfect prime number rulers are: 3, 4, 6, 8, 14, 18, 20, 24, 30, 32. There are 102 prime number rulers in total, 28 of which are minimal prime number rulers and 12 perfect prime number rulers.
a(n) is a finite subsequence of A008864.


LINKS



EXAMPLE

[0, 2, 3, 5, 7, 11, 17, 18] is a minimal and also a perfect prime number ruler.
[0, 2, 3, 5, 7, 11, 13, 19, 20] is a minimal but not a perfect prime number ruler.


CROSSREFS



KEYWORD

nonn,fini,full


AUTHOR



STATUS

approved



