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A303658
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Decimal expansion of the alternating sum of the reciprocals of the triangular numbers.
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2
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7, 7, 2, 5, 8, 8, 7, 2, 2, 2, 3, 9, 7, 8, 1, 2, 3, 7, 6, 6, 8, 9, 2, 8, 4, 8, 5, 8, 3, 2, 7, 0, 6, 2, 7, 2, 3, 0, 2, 0, 0, 0, 5, 3, 7, 4, 4, 1, 0, 2, 1, 0, 1, 6, 4, 8, 2, 7, 2, 0, 0, 3, 7, 9, 7, 3, 5, 7, 4, 4, 8, 7, 8, 7, 8, 7, 7, 8, 8, 6, 2, 4, 2, 3, 4, 5, 3
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OFFSET
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0,1
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LINKS
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FORMULA
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Equals log(16/e^2) = log(16) - 2.
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EXAMPLE
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1/1 - 1/3 + 1/6 - 1/10 + 1/15 - 1/21 + ... = 0.77258872223978123766892848583270627230200053744102...
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MATHEMATICA
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RealDigits[4*Log[2] - 2, 10, 100][[1]] (* Amiram Eldar, Aug 19 2020 *)
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PROG
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(PARI) sumalt(n=1, (-1)^(n+1)*2/(n*(n+1))) \\ Michel Marcus, Apr 28 2018
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CROSSREFS
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Apart from leading digit the same as A016639 (log(16)).
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KEYWORD
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AUTHOR
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STATUS
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approved
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