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A228184
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Numbers k such that k^2 + k + 41 is semiprime.
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3
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40, 41, 44, 49, 56, 65, 76, 81, 82, 84, 87, 89, 91, 96, 102, 104, 109, 117, 121, 122, 123, 126, 127, 130, 136, 138, 140, 143, 147, 155, 159, 161, 162, 163, 164, 170, 172, 173, 178, 184, 185, 186, 187, 190, 201, 204, 205, 207, 208, 209, 213, 215, 216, 217, 218
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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a(3) = 44 is in the sequence because 44^2 + 44 + 41 = 43*47 is semiprime.
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MATHEMATICA
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a = {}; Do[
If[PrimeOmega[x^2 + x + 41] == 2, AppendTo[a, x]], {x, 1, 500}]; a
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CROSSREFS
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KEYWORD
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nonn,less
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AUTHOR
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STATUS
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approved
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