OFFSET
1,2
COMMENTS
The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).
Also products of elements of A011757.
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {}
2: {1}
4: {1,1}
7: {4}
8: {1,1,1}
14: {1,4}
16: {1,1,1,1}
23: {9}
28: {1,1,4}
32: {1,1,1,1,1}
46: {1,9}
49: {4,4}
53: {16}
56: {1,1,1,4}
64: {1,1,1,1,1,1}
92: {1,1,9}
97: {25}
98: {1,4,4}
MATHEMATICA
Select[Range[100], And@@Cases[FactorInteger[#], {p_, _}:>IntegerQ[Sqrt[PrimePi[p]]]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 08 2019
STATUS
approved