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 A145976 Expansion of 1/(1-x*(1-7*x)). 8
 1, 1, -6, -13, 29, 120, -83, -923, -342, 6119, 8513, -34320, -93911, 146329, 803706, -220597, -5846539, -4302360, 36623413, 66739933, -189623958, -656803489, 670564217, 5268188640, 574239121, -36303081359, -40322755206, 213798814307 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Row sums of Riordan array (1,x(1-7x)). LINKS G. C. Greubel, Table of n, a(n) for n = 0..1500 Index entries for linear recurrences with constant coefficients, signature (1, -7). FORMULA a(n) = a(n-1) - 7*a(n-2), a(0)=1, a(1)=1. a(n) = Sum_{k=0..n} A109466(n,k)*7^(n-k). a(n) = -(1/18)*i*sqrt(3)*(1/2 + (3/2)*i*sqrt(3))^n + (1/18)*i*sqrt(3)*(1/2 - (3/2)*i*sqrt(3))^n + (1/2)*(1/2 - (3/2)*i*sqrt(3))^n + (1/2)*(1/2 + (3/2)*i*sqrt(3))^n, with n >= 0 and i=sqrt(-1). - Paolo P. Lava, Nov 18 2008 MATHEMATICA Join[{a=1, b=1}, Table[c=b-7*a; a=b; b=c, {n, 80}]] (* Vladimir Joseph Stephan Orlovsky, Jan 22 2011 *) CoefficientList[Series[1/(1-x(1-7x)), {x, 0, 50}], x] (* or *) LinearRecurrence[{1, -7}, {1, 1}, 50] (* Harvey P. Dale, May 11 2011 *) PROG (Sage) [lucas_number1(n, 1, 7) for n in range(1, 29)] # Zerinvary Lajos, Apr 22 2009 (PARI) Vec(1/(1-x*(1-7*x)) + O(x^40)) \\ Michel Marcus, Jan 29 2016 (MAGMA) I:=[1, 1]; [n le 2 select I[n] else Self(n-1) - 7*Self(n-2): n in [1..30]]; // G. C. Greubel, Jan 19 2018 CROSSREFS Cf. A010892, A107920, A106852, A106853, A106854, A145934. Sequence in context: A016071 A086652 A159694 * A101622 A256871 A192304 Adjacent sequences:  A145973 A145974 A145975 * A145977 A145978 A145979 KEYWORD sign,easy AUTHOR Philippe Deléham, Oct 26 2008 EXTENSIONS Corrected by Zerinvary Lajos, Apr 22 2009 Corrected by D. S. McNeil, Aug 20 2010 STATUS approved

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Last modified August 4 02:24 EDT 2021. Contains 346441 sequences. (Running on oeis4.)