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Search: id:A070006
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| A070006 |
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Arithmetical mean of distinct primes dividing n is a prime and n is neither a prime nor power of a prime. Subsequence of A070005. |
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+0
3
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| 21, 33, 57, 63, 69, 85, 93, 99, 105, 129, 133, 145, 147, 171, 177, 189, 195, 205, 207, 213, 217, 231, 237, 249, 253, 265, 279, 297, 309, 315, 363, 387, 393, 417, 425, 441, 445, 465, 469, 483, 489, 493, 505, 513, 517, 525, 531, 553, 565, 567, 573, 585, 597
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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n=993=3.331, mean=334/2=167, a prime
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MATHEMATICA
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ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] Do[s=Apply[Plus, ba[n]]/lf[n]; If[PrimeQ[s]&&Greater[lf[n], 1], Print[n]], {n, 2, 1000}]
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CROSSREFS
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Cf. A070005, A008472, A001414.
Sequence in context: A119973 A141249 A026068 this_sequence A084109 A016105 A032603
Adjacent sequences: A070003 A070004 A070005 this_sequence A070007 A070008 A070009
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KEYWORD
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easy,nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Apr 11 2002
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