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A017233
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a(n) = 9*n + 6.
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12
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6, 15, 24, 33, 42, 51, 60, 69, 78, 87, 96, 105, 114, 123, 132, 141, 150, 159, 168, 177, 186, 195, 204, 213, 222, 231, 240, 249, 258, 267, 276, 285, 294, 303, 312, 321, 330, 339, 348, 357, 366, 375, 384, 393, 402, 411, 420, 429, 438, 447, 456, 465, 474, 483
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OFFSET
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0,1
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COMMENTS
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Numbers whose digital root is 6; that is, A010888(a(n)) = 6. (Ball essentially says that Iamblichus (circa 350) announced that a number equal to the sum of three integers 3n, 3n - 1, and 3n - 2 has 6 as what is now called the number's digital root.) - Rick L. Shepherd, Apr 01 2014
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REFERENCES
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W. W. R. Ball, A Short Account of the History of Mathematics, Sterling Publishing Company, Inc., 2001 (Facsimile Edition) [orig. pub. 1912], pages 110-111.
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LINKS
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FORMULA
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Sum_{n>=0} (-1)^n/a(n) = sqrt(3)*Pi/27 - log(2)/9. - Amiram Eldar, Dec 12 2021
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MATHEMATICA
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LinearRecurrence[{2, -1}, {6, 15}, 60] (* Harvey P. Dale, Feb 01 2014 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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David J. Horn and Laura Krebs Gordon (lkg615(AT)verizon.net), 1985
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STATUS
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approved
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