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A328603
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Numbers whose prime indices have no consecutive divisible parts, meaning no prime index is a divisor of the next-smallest prime index, counted with multiplicity.
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9
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1, 2, 3, 5, 7, 11, 13, 15, 17, 19, 23, 29, 31, 33, 35, 37, 41, 43, 47, 51, 53, 55, 59, 61, 67, 69, 71, 73, 77, 79, 83, 85, 89, 91, 93, 95, 97, 101, 103, 105, 107, 109, 113, 119, 123, 127, 131, 137, 139, 141, 143, 145, 149, 151, 155, 157, 161, 163, 165, 167
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OFFSET
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1,2
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COMMENTS
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First differs from A304713 in having 105, with prime indices {2, 3, 4}.
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.
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LINKS
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FORMULA
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EXAMPLE
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The sequence of terms together with their prime indices begins:
1: {}
2: {1}
3: {2}
5: {3}
7: {4}
11: {5}
13: {6}
15: {2,3}
17: {7}
19: {8}
23: {9}
29: {10}
31: {11}
33: {2,5}
35: {3,4}
37: {12}
41: {13}
43: {14}
47: {15}
51: {2,7}
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MATHEMATICA
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primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[100], !MatchQ[primeMS[#], {___, x_, y_, ___}/; Divisible[y, x]]&]
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CROSSREFS
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These are the Heinz numbers of the partitions counted by A328171.
The version for relatively prime instead of indivisible is A328335.
Compositions without consecutive divisibilities are A328460.
Numbers whose binary indices lack consecutive divisibilities are A328593.
The version with all pairs indivisible is A304713.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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