OFFSET
1,4
COMMENTS
The reciprocal factorial sum of an integer partition (y_1,...,y_k) is 1/y_1! + ... + 1/y_k!.
EXAMPLE
The initial terms count the following partitions:
1: (1)
2: (1,1)
3: (1,1,1)
4: (2,2)
4: (1,1,1,1)
5: (2,2,1)
5: (1,1,1,1,1)
6: (2,2,1,1)
6: (1,1,1,1,1,1)
7: (2,2,1,1,1)
7: (1,1,1,1,1,1,1)
8: (2,2,2,2)
8: (2,2,1,1,1,1)
8: (1,1,1,1,1,1,1,1)
9: (2,2,2,2,1)
9: (2,2,1,1,1,1,1)
9: (1,1,1,1,1,1,1,1,1)
MATHEMATICA
Table[Length[Select[IntegerPartitions[n], IntegerQ[Total[1/(#!)]]&]], {n, 30}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, May 13 2019
STATUS
approved