STATUS
reviewed
approved
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Revision History for A109810
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Number of permutations of the positive divisors of n, where every element is coprime to its adjacent elements.
(history; published version)
(history; published version)
STATUS
proposed
reviewed
STATUS
editing
proposed
COMMENTS
Depends only on prime signature; a(A033942(n))=0; a(A037143(n))>0; a(A000430(n))=2; a(A006881(n))=4. - Reinhard Zumkeller, May 24 2010
LINKS
R. Reinhard Zumkeller, <a href="/A109810/b109810.txt">Table of n, a(n) for n = 1..10000</a>
FORMULA
a(A033942(n))=0; a(A037143(n))>0; a(A000430(n))=2; a(A006881(n))=4. - Reinhard Zumkeller, May 24 2010
STATUS
approved
editing
STATUS
proposed
approved
STATUS
editing
proposed
COMMENTS
LINKS
R. Zumkeller, <a href="/A109810/b109810.txt">Table of n, a(n) for n = 1..10000</a> [From _Reinhard Zumkeller_, May 24 2010]
EXAMPLE
The divisors of 6 are 1, 2, 3 and 6. Of the permutations of these integers, only (6,1,2,3), (6,1,3,2), (2,3,1,6) and (3,2,1,6) are such that every pair of adjacent elements is coprime.
only (6,1,2,3), (6,1,3,2), (2,3,1,6) and (3,2,1,6) are such that every pair of adjacent elements is coprime.
CROSSREFS
Cf. A178254. [From _- _Reinhard Zumkeller_, May 24 2010]
STATUS
approved
editing
AUTHOR
Leroy Quet , Aug 16 2005
AUTHOR
_Leroy Quet _ Aug 16 2005
EXTENSIONS
Terms 17 to 59 from _Diana L. Mecum (diana.mecum(AT)gmail.com), _, Jul 18 2008