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Search: id:A133019
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| A133019 |
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Product of n-th prime and n-th prime written backwards. |
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+0
7
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| 4, 9, 25, 49, 121, 403, 1207, 1729, 736, 2668, 403, 2701, 574, 1462, 3478, 1855, 5605, 976, 5092, 1207, 2701, 7663, 3154, 8722, 7663, 10201, 31003, 75007, 98209, 35143, 91567, 17161, 100147, 129409, 140209, 22801, 117907, 58843, 127087
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(8) = 1729 is the second taxicab number, also called the Hardy-Ramanujan number (See A001235, A011541 and A133029).
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FORMULA
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a(n) = A000040(n) * A004087(n)
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EXAMPLE
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a(8) = 1729 because the 8th prime is 19 and 19 written backwards is 91 and 19*91 = 1729.
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CROSSREFS
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Cf. A001235, A004087, A011541, A061205, A067563, A067087, A133029. Prime numbers: A000040.
Sequence in context: A052043 A030146 A001255 this_sequence A028866 A068373 A068888
Adjacent sequences: A133016 A133017 A133018 this_sequence A133020 A133021 A133022
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KEYWORD
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base,easy,nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Oct 27 2007
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