OFFSET
1,3
COMMENTS
The r-tuples correspond to the partitions of n and for each r-tuple, (Sum_{i=1..r} x_i)!/(Product_{i=1..r} x_i!) is the number of permutations of the corresponding partition. - David Wasserman, Apr 07 2008
EXAMPLE
a(4) = 3 because the 5 tuples (0, 0, 0, 1), (1, 0, 1), (0, 2), (2, 1) and (4) yield three different values, 1, 2 and 3: 1!/1! = 1, 2!/1!*1! = 2, 2!/2! = 1, 3!/2!*1! = 3 and 4!/4! = 1.
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, Feb 23 2005
EXTENSIONS
More terms and better description from David Wasserman, Apr 07 2008
STATUS
approved