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A324856
Numbers divisible by exactly one of their prime indices.
9
2, 10, 14, 15, 22, 26, 34, 38, 45, 46, 50, 55, 58, 62, 70, 74, 82, 86, 94, 98, 105, 106, 118, 119, 122, 130, 134, 135, 142, 146, 154, 158, 166, 170, 178, 182, 190, 194, 195, 202, 206, 207, 214, 218, 226, 230, 242, 250, 254, 255, 262, 266, 274, 275, 278, 285
OFFSET
1,1
COMMENTS
Numbers n such that A324848(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.
If k is in A324846, then k*prime(k) is in the sequence. - Robert Israel, Mar 22 2019
LINKS
EXAMPLE
The sequence of terms together with their prime indices begins:
2: {1}
10: {1,3}
14: {1,4}
15: {2,3}
22: {1,5}
26: {1,6}
34: {1,7}
38: {1,8}
45: {2,2,3}
46: {1,9}
50: {1,3,3}
55: {3,5}
58: {1,10}
62: {1,11}
70: {1,3,4}
74: {1,12}
82: {1,13}
86: {1,14}
94: {1,15}
98: {1,4,4}
MAPLE
filter:= proc(n) local F;
F:= select(t -> n mod numtheory:-pi(t[1])=0, ifactors(n)[2]);
nops(F)=1 and F[1][2]=1
end proc:
select(filter, [$2..1000]); # Robert Israel, Mar 22 2019
MATHEMATICA
Select[Range[100], Total[Cases[If[#==1, {}, FactorInteger[#]], {p_, k_}:>k/; Divisible[#, PrimePi[p]]]]==1&]
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 21 2019
STATUS
approved