OFFSET
1,1
COMMENTS
A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
EXAMPLE
The terms together with their corresponding multiset multisystems (A302242):
7: {{1,1}}
9: {{1},{1}}
14: {{},{1,1}}
18: {{},{1},{1}}
19: {{1,1,1}}
21: {{1},{1,1}}
23: {{2,2}}
25: {{2},{2}}
27: {{1},{1},{1}}
28: {{},{},{1,1}}
36: {{},{},{1},{1}}
38: {{},{1,1,1}}
42: {{},{1},{1,1}}
46: {{},{2,2}}
49: {{1,1},{1,1}}
50: {{},{2},{2}}
53: {{1,1,1,1}}
54: {{},{1},{1},{1}}
56: {{},{},{},{1,1}}
57: {{1},{1,1,1}}
63: {{1},{1},{1,1}}
72: {{},{},{},{1},{1}}
76: {{},{},{1,1,1}}
81: {{1},{1},{1},{1}}
MATHEMATICA
Select[Range[100], GCD@@FactorInteger[Times@@Cases[FactorInteger[#], {p_, k_}:>PrimePi[p]^k]][[All, 2]]>1&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 10 2018
STATUS
approved