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.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
The sequence of terms together with their prime indices begins:
30: {1,2,3}
65: {3,6}
154: {1,4,5}
165: {2,3,5}
190: {1,3,8}
259: {4,12}
273: {2,4,6}
385: {3,4,5}
390: {1,2,3,6}
435: {2,3,10}
442: {1,6,7}
481: {6,12}
506: {1,5,9}
561: {2,5,7}
595: {3,4,7}
609: {2,4,10}
658: {1,4,15}
714: {1,2,4,7}
741: {2,6,8}
781: {5,20}
MATHEMATICA
primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[2, 1000], !PrimeQ[#]&&SquareFreeQ[#]&&Divisible[Times@@primeMS[#], Plus@@primeMS[#]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jun 10 2019
STATUS
approved