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Search: id:A152101
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| A152101 |
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Semiprimes based on powers of two and primes: a(n)=16^n - 3*2^(2*n - 1) - 1=(2^(2*n - 1) - 1)*(2^(2*n + 1) + 1) |
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+0
1
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| 9, 231, 3999, 65151, 1047039, 16771071, 268410879, 4294868991, 68719083519, 1099510054911, 17592179752959, 281474951544831, 4503599526707199, 72057593635274751, 1152921502996234239, 18446744067267100671
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Idea resulted from seqfan posts by Artur Jasinski (grafix(AT)csl.pl).
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FORMULA
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a(n)=16^n - 3*2^(2*n - 1) - 1=(2^(2*n - 1) - 1)*(2^(2*n + 1) + 1).
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MATHEMATICA
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b[n_] := 16^n - 3*2^(2*n - 1) - 1. Table[b[n], {n, 1, 30}]
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CROSSREFS
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Sequence in context: A095363 A138564 A158728 this_sequence A165389 A153223 A157569
Adjacent sequences: A152098 A152099 A152100 this_sequence A152102 A152103 A152104
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KEYWORD
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nonn
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Nov 24 2008
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