OFFSET
1,1
COMMENTS
The Heinz number of a partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). This gives a bijective correspondence between positive integers and integer partitions.
FORMULA
A257991(a(n)) > 0.
EXAMPLE
The terms together with their prime indices begin:
2: {1}
4: {1,1}
5: {3}
6: {1,2}
8: {1,1,1}
10: {1,3}
11: {5}
12: {1,1,2}
14: {1,4}
15: {2,3}
16: {1,1,1,1}
17: {7}
18: {1,2,2}
20: {1,1,3}
22: {1,5}
23: {9}
24: {1,1,1,2}
MATHEMATICA
Select[Range[100], Or@@OddQ/@PrimePi/@First/@FactorInteger[#]&]
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 14 2023
STATUS
approved