OFFSET
1,1
COMMENTS
EXAMPLE
The sequence of terms together with their prime indices begins:
21: {2,4} 126: {1,2,2,4} 203: {4,10}
39: {2,6} 129: {2,14} 210: {1,2,3,4}
42: {1,2,4} 130: {1,3,6} 213: {2,20}
57: {2,8} 133: {4,8} 222: {1,2,12}
63: {2,2,4} 147: {2,4,4} 228: {1,1,2,8}
65: {3,6} 156: {1,1,2,6} 230: {1,3,9}
78: {1,2,6} 159: {2,16} 231: {2,4,5}
84: {1,1,2,4} 168: {1,1,1,2,4} 234: {1,2,2,6}
87: {2,10} 171: {2,2,8} 235: {3,15}
91: {4,6} 174: {1,2,10} 237: {2,22}
105: {2,3,4} 182: {1,4,6} 247: {6,8}
111: {2,12} 183: {2,18} 252: {1,1,2,2,4}
114: {1,2,8} 185: {3,12} 258: {1,2,14}
115: {3,9} 189: {2,2,2,4} 259: {4,12}
117: {2,2,6} 195: {2,3,6} 260: {1,1,3,6}
MATHEMATICA
Select[Range[2, 100], !PrimePowerQ[#]&&!CoprimeQ@@Union[PrimePi/@First/@FactorInteger[#]]&]
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 12 2020
STATUS
approved