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Search: id:A113839
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| A113839 |
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Powerful(1) numbers sandwiched between twin primes. |
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+0
1
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| 4, 72, 108, 432, 1152, 2592, 3528, 9000, 18252, 20808, 21600, 34848, 49392, 69192, 83232, 103968, 139968, 180000, 197568, 264600, 345600, 362952, 438048, 444528, 472392, 649800, 734472, 808992, 995328, 1143072, 1190700, 1254528, 1529388
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Here we are considering powerful numbers (first definition) A001694.
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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EXAMPLE
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72 is powerful(1) since 72=2^3*3^2 and 71 and 73 are twin primes.
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MATHEMATICA
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pwfQ[n_] := n == 1 || Min[Transpose[FactorInteger@n][[2]]] > 1; lst={}; Do[If[PrimeQ[n-1] && PrimeQ[n+1] && pwfQ[n], AppendTo[lst, n]], {n, 4, 2*10^6, 4}]; lst
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CROSSREFS
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Cf. A001694, A001097.
Sequence in context: A133003 A132097 A128062 this_sequence A077112 A095385 A071683
Adjacent sequences: A113836 A113837 A113838 this_sequence A113840 A113841 A113842
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KEYWORD
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easy,nonn
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AUTHOR
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Giovanni Resta (g.resta(AT)iit.cnr.it), Jan 24 2006
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