OFFSET
1,3
COMMENTS
Previous terms can appear in any order but can be used at most once. - Paolo P. Lava, Mar 04 2010
EXAMPLE
465 is not in the sequence because 4 U 6 U 5 -> 465;
466 is not in the sequence because 4 U 66 -> 466;
1313 is not in the sequence because 1 U 313 or 131 U 3 -> 1313.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Paolo P. Lava and Giorgio Balzarotti, Jul 30 2008, Aug 04 2008
EXTENSIONS
Corrected by Paolo P. Lava, Mar 03 2010
STATUS
approved