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A326158
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Nonprime squarefree numbers whose product of prime indices is divisible by their sum of prime indices.
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11
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30, 65, 154, 165, 190, 259, 273, 385, 390, 435, 442, 481, 506, 561, 595, 609, 658, 714, 741, 781, 874, 935, 1001, 1110, 1118, 1173, 1254, 1281, 1330, 1363, 1403, 1430, 1455, 1469, 1495, 1505, 1653, 1691, 1771, 1786, 1794, 1798, 1887, 1958, 2035, 2067, 2139
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OFFSET
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1,1
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COMMENTS
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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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EXAMPLE
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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}
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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[2, 1000], !PrimeQ[#]&&SquareFreeQ[#]&&Divisible[Times@@primeMS[#], Plus@@primeMS[#]]&]
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CROSSREFS
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The case with squarefree numbers included is A326150.
The case with primes and squarefree numbers included is A326149.
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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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