OFFSET
1,2
COMMENTS
The positions where 1, 2, 3, 4, 5, ... appear are 1, 2, 5, 15, 52, ... (Bell numbers A000110).
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Aug 14 2003
EXTENSIONS
Extended by Philippe Deléham, Jun 10 2005
STATUS
approved