OFFSET
1,2
EXAMPLE
E.g., going from r(4)=2 to r(5)=7 to r(6)=13 we increase twice in a row, so 6 is a member. Going from r(21)=63 to r(22)=41 to r(23)=18 we decrease twice in a row, so 23 is a member.
CROSSREFS
KEYWORD
nonn
AUTHOR
Allan Wilks, Oct 30 2001
EXTENSIONS
Better description from Dean Hickerson, Feb 15 2006
STATUS
approved