OFFSET
1,2
COMMENTS
LINKS
EXAMPLE
The terms together with their prime indices begin:
1: {} 17: {7} 35: {3,4}
2: {1} 19: {8} 37: {12}
3: {2} 20: {1,1,3} 38: {1,8}
4: {1,1} 22: {1,5} 39: {2,6}
5: {3} 23: {9} 40: {1,1,1,3}
7: {4} 25: {3,3} 41: {13}
8: {1,1,1} 26: {1,6} 43: {14}
9: {2,2} 27: {2,2,2} 44: {1,1,5}
10: {1,3} 28: {1,1,4} 45: {2,2,3}
11: {5} 29: {10} 46: {1,9}
13: {6} 31: {11} 47: {15}
14: {1,4} 32: {1,1,1,1,1} 49: {4,4}
15: {2,3} 33: {2,5} 50: {1,3,3}
16: {1,1,1,1} 34: {1,7} 51: {2,7}
MATHEMATICA
prix[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[100], UnsameQ@@DeleteCases[Differences[Prepend[prix[#], 0]], 0]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 13 2025
STATUS
approved
