OFFSET
1,1
COMMENTS
EXAMPLE
The sequence of terms together with their prime indices begins:
2: {1}
3: {2}
5: {3}
9: {2,2}
11: {5}
15: {2,3}
23: {9}
25: {3,3}
27: {2,2,2}
31: {11}
33: {2,5}
45: {2,2,3}
47: {15}
55: {3,5}
69: {2,9}
75: {2,3,3}
81: {2,2,2,2}
83: {23}
93: {2,11}
97: {25}
99: {2,2,5}
MATHEMATICA
aQ[n_]:=Switch[n, 1, False, 2, True, _, And@@Cases[FactorInteger[n], {p_, k_}:>aQ[PrimePi[p]]]];
Select[Range[100], aQ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 10 2019
STATUS
approved