OFFSET
1,2
COMMENTS
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {} 30: {1,2,3}
2: {1} 32: {1,1,1,1,1}
3: {2} 36: {1,1,2,2}
4: {1,1} 40: {1,1,1,3}
6: {1,2} 48: {1,1,1,1,2}
8: {1,1,1} 54: {1,2,2,2}
9: {2,2} 56: {1,1,1,4}
10: {1,3} 60: {1,1,2,3}
12: {1,1,2} 64: {1,1,1,1,1,1}
16: {1,1,1,1} 72: {1,1,1,2,2}
18: {1,2,2} 80: {1,1,1,1,3}
20: {1,1,3} 81: {2,2,2,2}
24: {1,1,1,2} 84: {1,1,2,4}
27: {2,2,2} 88: {1,1,1,5}
28: {1,1,4} 90: {1,2,2,3}
MATHEMATICA
Select[Range[100], PrimeOmega[#]>=Total[Cases[FactorInteger[#], {p_, k_}:>k*PrimePi[p]]]/2&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 16 2021
STATUS
approved