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A175794
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a(n) = Sum_{k=1..n} (-1)^A001620(k).
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2
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-1, -2, -3, -2, -3, -4, -3, -2, -1, -2, -1, -2, -3, -4, -3, -2, -1, 0, 1, 2, 3, 2, 1, 2, 3, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 9, 10, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 2, 1, 0, -1, 0, 1, 2, 1, 0, 1, 0, 1, 0, 1, 2, 3, 4, 5, 6, 5, 4, 5, 6, 5, 4, 3, 4, 5, 6, 7, 6, 7, 6, 5, 6, 5, 6, 5, 6, 7, 6, 7, 6, 5, 4, 5
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OFFSET
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1,2
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LINKS
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EXAMPLE
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a(6) = -4 is in the sequence because -4 = (-1)^5 + (-1)^7 + (-1)^7 + (-1)^2 + (-1)^1 + (-1)^5
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MAPLE
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with(numtheory):T:=array(1..201): Digits:=200:nn:=10^200:a:=floor(evalf(gamma(0))*nn): n:=a:l:=length(n):n0:=n:s:=0:for m from 1 to l do:q:=n0:u:=irem(q, 10):v:=iquo(q, 10):n0:=v :T[m]:=u:od: for p from l to 1 by -1 do:s:=s+(-1)^T[p]: printf(`%d, `, s):od:
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MATHEMATICA
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Rest@ FoldList[ Plus, 0, (-1)^First@ RealDigits[EulerGamma, 10, 200]] (* or *) Accumulate[(-1)^RealDigits[EulerGamma, 10, 100][[1]]] (* Harvey P. Dale, May 11 2014 *)
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CROSSREFS
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A001620 is the decimal expansion of Euler's constant (or Euler-Mascheroni constant) gamma.
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KEYWORD
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sign,obsc,less,base
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AUTHOR
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STATUS
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approved
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