OFFSET
1,2
EXAMPLE
1: 1, 2: 2, 3: 2 3, 4: 3 4, 5: 4 5 6, 6: 4 5 6, 7: 7 10 12...
Permutations of 7 elements have orders of 1, 2, 3, 4, 5, 6, 7, 10, 12, of which 7, 10 and 12 are not factors of any others.
CROSSREFS
KEYWORD
easy,nonn,tabf
AUTHOR
Allen Tracht (atracht(AT)ix.netcom.com), Dec 08 2005
STATUS
approved