OFFSET
1,1
COMMENTS
EXAMPLE
The even prime indices of 91 are {4,6}, halved {2,3}, which are relatively prime, so 91 is in the sequence.
The prime indices of 665 are {3,4,8}, even {4,8}, halved {2,4}, which are not relatively prime, so 665 is not in the sequence.
The terms together with their prime indices begin:
3: {2}
6: {1,2}
9: {2,2}
12: {1,1,2}
15: {2,3}
18: {1,2,2}
21: {2,4}
24: {1,1,1,2}
27: {2,2,2}
30: {1,2,3}
33: {2,5}
36: {1,1,2,2}
39: {2,6}
42: {1,2,4}
45: {2,2,3}
48: {1,1,1,1,2}
MATHEMATICA
Select[Range[100], GCD@@Select[PrimePi/@First/@FactorInteger[#], EvenQ]/2==1&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 31 2023
STATUS
approved