OFFSET
2,5
COMMENTS
EXAMPLE
Let n=12, 2n-1=23. Considering periodic sequence <+>,<->,<+>,<->,..., we have 23<+>1=3, 23<->3=5, 23<+>5=7, 23<->7=1, 23<+>1=3,... Thus a(12)<=4. It is not difficult to verify that a(12)>3. Thus a(12)=4.
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Jul 18 2010
STATUS
approved