OFFSET
1,2
COMMENTS
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
The reciprocal factorial sum of an integer partition (y_1,...,y_k) is 1/y_1! + ... + 1/y_k!.
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {}
2: {1}
3: {2}
5: {3}
7: {4}
9: {2,2}
11: {5}
13: {6}
17: {7}
19: {8}
23: {9}
25: {3,3}
29: {10}
31: {11}
37: {12}
41: {13}
43: {14}
47: {15}
49: {4,4}
53: {16}
MATHEMATICA
Select[Range[100], IntegerQ[1/Total[Cases[FactorInteger[#], {p_, k_}:>k/PrimePi[p]!]]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 13 2019
STATUS
approved