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A162385
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Alternating sum from the n-th Mersenne prime up to the n-th perfect number.
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0
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2, 11, 233, 4001, 16771073, 4294868993, 68719083521, 1152921502996234241, 1329227995784915871174424803370074113, 95780971304118053647396688732666809244153592049303553
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OFFSET
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1,1
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COMMENTS
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Define the alternating sum S(k) = sum_{x=0..k} x*(-1)^x = (-1)^k*(k/2+1/4)-1/4 = A130472(k).
a(n) is this sum evaluated with a lower limit of A000668(n) and an upper limit of A000396(n).
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LINKS
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FORMULA
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EXAMPLE
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a(1) = -3+4-5+6 = 2. a(2) = -7+8-9+10-11+12-13+14-15+16-17+...-27+28 = 11.
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CROSSREFS
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KEYWORD
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nonn,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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