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A054586
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a(n) = Sum_{d|2n+1} phi(d)*mu(d).
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0
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1, -1, -3, -5, -1, -9, -11, 3, -15, -17, 5, -21, -3, -1, -27, -29, 9, 15, -35, 11, -39, -41, 3, -45, -5, 15, -51, 27, 17, -57, -59, 5, 33, -65, 21, -69, -71, 3, 45, -77, -1, -81, 45, 27, -87, 55, 29, 51, -95, 9, -99, -101, -15, -105, -107, 35, -111, 63, 11, 75, -9
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OFFSET
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0,3
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REFERENCES
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David M. Burton, Elementary Number Theory, Allyn and Bacon Inc., Boston, MA, 1976, p. 152.
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LINKS
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FORMULA
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MATHEMATICA
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a[n_] := DivisorSum[2*n+1, MoebiusMu[#]*EulerPhi[#]&]; Table[a[n], {n, 0, 70}] (* Jean-François Alcover, Dec 03 2015 *)
f[p_, e_] := 2-p; a[n_] := Times @@ f @@@ FactorInteger[2*n+1]; Array[a, 100, 0] (* Amiram Eldar, Aug 12 2023 *)
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PROG
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(PARI) j=[]; for(n=0, 200, j=concat(j, sumdiv(2*n+1, d, moebius(d)*eulerphi(d)))); j
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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