OFFSET
1,2
COMMENTS
LINKS
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {} 28: {1,1,4} 52: {1,1,6}
2: {1} 30: {1,2,3} 54: {1,2,2,2}
4: {1,1} 32: {1,1,1,1,1} 55: {3,5}
6: {1,2} 33: {2,5} 56: {1,1,1,4}
8: {1,1,1} 34: {1,7} 58: {1,10}
10: {1,3} 35: {3,4} 60: {1,1,2,3}
12: {1,1,2} 36: {1,1,2,2} 62: {1,11}
14: {1,4} 38: {1,8} 64: {1,1,1,1,1,1}
15: {2,3} 40: {1,1,1,3} 66: {1,2,5}
16: {1,1,1,1} 44: {1,1,5} 68: {1,1,7}
18: {1,2,2} 45: {2,2,3} 69: {2,9}
20: {1,1,3} 46: {1,9} 70: {1,3,4}
22: {1,5} 48: {1,1,1,1,2} 72: {1,1,1,2,2}
24: {1,1,1,2} 50: {1,3,3} 74: {1,12}
26: {1,6} 51: {2,7} 75: {2,3,3}
MATHEMATICA
nn=100;
dat=Select[Range[nn], CoprimeQ@@PrimePi/@First/@FactorInteger[#]&];
facsusing[s_, n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facsusing[Select[s, Divisible[n/d, #]&], n/d], Min@@#>=d&]], {d, Select[s, Divisible[n, #]&]}]];
Select[Range[nn], facsusing[dat, #]!={}&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Aug 02 2020
STATUS
approved