OFFSET
1,2
COMMENTS
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {}
4: {1,1}
6: {1,2}
8: {1,1,1}
10: {1,3}
12: {1,1,2}
14: {1,4}
16: {1,1,1,1}
18: {1,2,2}
20: {1,1,3}
21: {2,4}
22: {1,5}
24: {1,1,1,2}
26: {1,6}
28: {1,1,4}
30: {1,2,3}
32: {1,1,1,1,1}
34: {1,7}
35: {3,4}
36: {1,1,2,2}
MATHEMATICA
aQ[n_]:=Switch[n, 1, True, _?PrimeQ, False, _, !And@@Cases[FactorInteger[n], {p_, k_}:>!aQ[PrimePi[p]]]];
Select[Range[200], aQ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 11 2019
STATUS
approved