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 odd prime indices of 345 are {3,9}, which are not relatively prime, so 345 is not in the sequence.
The odd prime indices of 825 are {3,3,5}, which are relatively prime, so 825 is in the sequence
The terms together with their prime indices begin:
55: {3,5}
85: {3,7}
155: {3,11}
165: {2,3,5}
187: {5,7}
205: {3,13}
253: {5,9}
255: {2,3,7}
275: {3,3,5}
295: {3,17}
335: {3,19}
341: {5,11}
385: {3,4,5}
391: {7,9}
415: {3,23}
425: {3,3,7}
451: {5,13}
465: {2,3,11}
485: {3,25}
495: {2,2,3,5}
MATHEMATICA
Select[Range[1000], OddQ[#]&&GCD@@Select[PrimePi/@First/@FactorInteger[#], OddQ]==1&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 01 2023
STATUS
approved