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A338910
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Numbers of the form prime(x) * prime(y) where x and y are both odd.
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14
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4, 10, 22, 25, 34, 46, 55, 62, 82, 85, 94, 115, 118, 121, 134, 146, 155, 166, 187, 194, 205, 206, 218, 235, 253, 254, 274, 289, 295, 298, 314, 334, 335, 341, 358, 365, 382, 391, 394, 415, 422, 451, 454, 466, 482, 485, 514, 515, 517, 527, 529, 538, 545, 554
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OFFSET
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1,1
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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:
4: {1,1} 146: {1,21} 314: {1,37}
10: {1,3} 155: {3,11} 334: {1,39}
22: {1,5} 166: {1,23} 335: {3,19}
25: {3,3} 187: {5,7} 341: {5,11}
34: {1,7} 194: {1,25} 358: {1,41}
46: {1,9} 205: {3,13} 365: {3,21}
55: {3,5} 206: {1,27} 382: {1,43}
62: {1,11} 218: {1,29} 391: {7,9}
82: {1,13} 235: {3,15} 394: {1,45}
85: {3,7} 253: {5,9} 415: {3,23}
94: {1,15} 254: {1,31} 422: {1,47}
115: {3,9} 274: {1,33} 451: {5,13}
118: {1,17} 289: {7,7} 454: {1,49}
121: {5,5} 295: {3,17} 466: {1,51}
134: {1,19} 298: {1,35} 482: {1,53}
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MAPLE
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q:= n-> (l-> add(i[2], i=l)=2 and andmap(i->
numtheory[pi](i[1])::odd, l))(ifactors(n)[2]):
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MATHEMATICA
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Select[Range[100], PrimeOmega[#]==2&&OddQ[Times@@PrimePi/@First/@FactorInteger[#]]&]
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CROSSREFS
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A338911 is the even instead of odd version.
A001221 counts distinct prime indices.
A300912 lists semiprimes with relatively prime indices.
A318990 lists semiprimes with divisible indices.
A338904 groups semiprimes by weight.
A338909 lists semiprimes with non-relatively prime indices.
Cf. A005117, A037143, A055684, A056239, A065516, A112798, A195017, A320655, A320732, A320892, A339004.
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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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