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Search: id:A135212
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| 1, 1, 2, 4, 8, 576, 1152, 2304, 4608, 18432, 552960, 59719680, 2388787200, 100329062400, 200658124800, 802632499200, 1605264998400, 288947699712000, 6356849393664000, 444979457556480000, 10679506981355520000
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OFFSET
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1,3
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COMMENT
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A078456(n) = {1, 3, 14, 92, 968, 12096, 199296, ...} = Number of numbers less than p(1)*p(2)*...*p(n) having exactly one prime factor among (p(1),p(2)....,p(n)) where p(n) is the n-th prime. A120271(n) = {1, 3, 7, 23, 121, 21, 173, 1597, 17927, ...} = Numerator of Sum[ 1/(Prime[k]-1), {k,1,n}].
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FORMULA
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a(n) = A078456(n)/A120271(n).
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MATHEMATICA
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Table[ Det[ DiagonalMatrix[ Table[ Prime[i+1]-1, {i, 1, n-1} ] ] + 1 ], {n, 1, 50} ] / Numerator[ Table[ Sum[ 1/(Prime[i]-1), {i, 1, n} ], {n, 1, 50}] ]
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CROSSREFS
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Cf. A078456, A120271.
Sequence in context: A082613 A061089 A067499 this_sequence A012456 A071686 A103097
Adjacent sequences: A135209 A135210 A135211 this_sequence A135213 A135214 A135215
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KEYWORD
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nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 23 2007
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