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A261890
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Second differences of A055615, first differences of A261869.
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4
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2, 4, -8, 16, -24, 20, -7, 10, -31, 32, -24, 40, -26, -16, -2, 34, -36, 38, 2, -20, -46, 68, -23, 26, -52, 26, -29, 28, 0, 32, 2, -32, 0, -36, -2, 112, -74, -40, -2, 40, 0, 44, -43, 46, -139, 140, -47, 0, 51, -102, -2, 106, 2, -110, 112, -56, -118, 176, -120
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OFFSET
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1,1
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COMMENTS
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a(n) = (n+2)*mu(n+2) - 2*(n+1)*mu(n+1) + n*mu(n), where mu = A008683 (Moebius function);
abs(a(n)) <= 4*(n+1).
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LINKS
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FORMULA
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MATHEMATICA
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Differences[Table[n MoebiusMu[n], {n, 80}], 2] (* Harvey P. Dale, Mar 12 2023 *)
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PROG
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(Haskell)
import Data.List (genericIndex)
a261890 n = genericIndex a261890_list (n - 1)
a261890_list = zipWith (-) (tail a261869_list) a261869_list
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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