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A323440
Numbers divisible by exactly one of their distinct prime indices.
7
2, 4, 8, 10, 14, 15, 16, 20, 22, 26, 32, 34, 38, 40, 44, 45, 46, 50, 52, 55, 58, 62, 64, 68, 70, 74, 75, 76, 80, 82, 86, 88, 92, 94, 98, 100, 104, 105, 106, 116, 118, 119, 122, 124, 128, 130, 134, 135, 136, 142, 146, 148, 154, 158, 160, 164, 166, 170, 172, 176
OFFSET
1,1
COMMENTS
Numbers n such that A324852(n) = 1.
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
EXAMPLE
The sequence of terms together with their prime indices begins:
2: {1}
4: {1,1}
8: {1,1,1}
10: {1,3}
14: {1,4}
15: {2,3}
16: {1,1,1,1}
20: {1,1,3}
22: {1,5}
26: {1,6}
32: {1,1,1,1,1}
34: {1,7}
38: {1,8}
40: {1,1,1,3}
44: {1,1,5}
45: {2,2,3}
46: {1,9}
50: {1,3,3}
52: {1,1,6}
55: {3,5}
MATHEMATICA
Select[Range[100], Count[If[#==1, {}, FactorInteger[#]], {p_, _}/; Divisible[#, PrimePi[p]]]==1&]
PROG
(PARI) isok(n) = my(f=factor(n)[, 1]); sum(k=1, #f, (n % primepi(f[k])) == 0) == 1; \\ Michel Marcus, Mar 22 2019
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 21 2019
STATUS
approved