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.
A number is squarefree if it is not divisible by any perfect square > 1.
A number has consecutive prime factors if it is divisible by both prime(k) and prime(k+1) for some k.
LINKS
EXAMPLE
The terms together with their prime indices begin:
2: {1}
6: {1,2}
10: {1,3}
14: {1,4}
15: {2,3}
22: {1,5}
26: {1,6}
30: {1,2,3}
34: {1,7}
35: {3,4}
38: {1,8}
42: {1,2,4}
46: {1,9}
58: {1,10}
62: {1,11}
66: {1,2,5}
70: {1,3,4}
MATHEMATICA
primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[100], Min@@Differences[Prepend[primeMS[#], 0]]==1&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jul 10 2022
STATUS
approved