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Search: id:A111371
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| A111371 |
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A number n is included if at least one prime dividing n is equal to an exponent of the highest power of any prime dividing n. |
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+0
1
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| 4, 12, 18, 20, 24, 27, 28, 36, 44, 50, 52, 54, 60, 68, 72, 76, 84, 90, 92, 98, 100, 108, 116, 120, 124, 126, 132, 135, 140, 144, 148, 150, 156, 160, 164, 168, 172, 180, 188, 189, 196, 198, 200, 204, 212, 216, 220, 228, 234, 236, 242, 244, 252, 260, 264, 268, 270
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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50 = 2^1 * 5^2. 2 is both a prime dividing 50 and the exponent of the highest power of 5 dividing 50. So 50 is in the sequence.
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MATHEMATICA
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Select[Range[2, 300], Intersection @@ Transpose[FactorInteger[ # ]] != {} &] (*Chandler*)
fQ[n_] := Block[{fi = FactorInteger[n]}, Position[ First[ # ] & /@ fi, Max[ Last[ # ] & /@ fi]] != {}]; Select[ Range[2, 291], fQ[ # ] &] (* Robert G. Wilson v *)
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CROSSREFS
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Sequence in context: A045042 A134860 A047958 this_sequence A078514 A074285 A057311
Adjacent sequences: A111368 A111369 A111370 this_sequence A111372 A111373 A111374
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Nov 08 2005
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net) and Robert G. Wilson v (rgwv(at)rgwv.com), Nov 09 2005
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