OFFSET
1,2
COMMENTS
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {}
3: {2}
5: {3}
9: {2,2}
11: {5}
13: {6}
15: {2,3}
17: {7}
19: {8}
25: {3,3}
27: {2,2,2}
29: {10}
31: {11}
33: {2,5}
37: {12}
39: {2,6}
41: {13}
43: {14}
45: {2,2,3}
MATHEMATICA
Select[Range[100], !MemberQ[If[#==1, {}, FactorInteger[#]], {p_, _}/; IntegerQ[Sqrt[PrimePi[p]]]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Apr 01 2019
STATUS
approved