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Search: id:A127959
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| A127959 |
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Nonprime numbers of the form 1 + Sum_{k=1..m} [2^(2k-1]]. |
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+0
1
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| 171, 10923, 699051, 11184811, 44739243, 178956971, 2863311531, 11453246123, 45812984491, 183251937963, 733007751851, 11728124029611, 46912496118443, 187649984473771, 750599937895083, 3002399751580331, 12009599006321323
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Prime numbers of the form 1+Sum[2^(2n-1]] is A000979. Numbers x such 1+Sum[2^(2n-1]] is prime for n=1,2,...,x is A127936. A127955 is probably a subset of the present sequence..
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MATHEMATICA
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a = {}; Do[c = 1 + Sum[2^(2n - 1), {n, 1, x}]; If[PrimeQ[c] == False, AppendTo[a, c]], {x, 1, 50}]; a
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CROSSREFS
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Cf. A000979, A000978, A124400, A126614, A127955, A127956, A127957, A127958, A127936.
Adjacent sequences: A127956 A127957 A127958 this_sequence A127960 A127961 A127962
Sequence in context: A079654 A036518 A016058 this_sequence A046166 A097844 A076573
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Feb 09 2007
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