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A014992
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a(n) = (1 - (-10)^n)/11.
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9
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1, -9, 91, -909, 9091, -90909, 909091, -9090909, 90909091, -909090909, 9090909091, -90909090909, 909090909091, -9090909090909, 90909090909091, -909090909090909, 9090909090909091, -90909090909090909
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OFFSET
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1,2
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COMMENTS
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q-integers for q = -10.
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LINKS
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FORMULA
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a(n) = a(n-1) + q^(n-1) = (q^n - 1) / (q - 1).
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MAPLE
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a:=n->sum ((-10)^j, j=0..n): seq(a(n), n=0..25); # Zerinvary Lajos, Dec 16 2008
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MATHEMATICA
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CoefficientList[Series[1/((1 - x)*(1 + 10*x)), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 22 2012 *)
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PROG
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(Sage) [gaussian_binomial(n, 1, -10) for n in range(1, 19)] # Zerinvary Lajos, May 28 2009
(Magma) I:=[1, -9]; [n le 2 select I[n] else -9*Self(n-1) +10*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Oct 22 2012
(PARI) for(n=1, 30, print1((1-(-10)^n)/11, ", ")) \\ G. C. Greubel, May 26 2018
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CROSSREFS
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Cf. A077925, A014983, A014985, A014986, A014987, A014989, A014990, A014991, A014993, A014994. - Zerinvary Lajos, Dec 16 2008
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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