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 A195043 Concentric 11-gonal numbers. 7
 0, 1, 11, 23, 44, 67, 99, 133, 176, 221, 275, 331, 396, 463, 539, 617, 704, 793, 891, 991, 1100, 1211, 1331, 1453, 1584, 1717, 1859, 2003, 2156, 2311, 2475, 2641, 2816, 2993, 3179, 3367, 3564, 3763, 3971, 4181, 4400, 4621, 4851, 5083, 5324, 5567 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Also concentric hendecagonal numbers. A033584 and A069173 interleaved. Partial sums of A175885. - Reinhard Zumkeller, Jan 07 2012 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1). FORMULA a(n) = 11*n^2/4 + 7*((-1)^n - 1)/8. a(n) = -a(n-1) + A069125(n). - Vincenzo Librandi, Sep 30 2011 From Colin Barker, Sep 15 2013: (Start) a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4). G.f.: -x*(x^2+9*x+1) / ((x-1)^3*(x+1)). (End) MATHEMATICA LinearRecurrence[{2, 0, -2, 1}, {0, 1, 11, 23}, 50] (* Harvey P. Dale, May 20 2019 *) PROG (MAGMA) [11*n^2/4+7*((-1)^n-1)/8: n in [0..50]]; // Vincenzo Librandi, Sep 30 2011 (Haskell) a195043 n = a195043_list !! n a195043_list = scanl (+) 0 a175885_list -- Reinhard Zumkeller, Jan 07 2012 (PARI) Vec(-x*(x^2+9*x+1)/((x-1)^3*(x+1)) + O(x^100)) \\ Colin Barker, Sep 15 2013 CROSSREFS Column 11 of A195040. Cf. A032527, A032528, A195042, A195142, A195143, A195045. Sequence in context: A228444 A191235 A146451 * A029468 A198588 A068231 Adjacent sequences:  A195040 A195041 A195042 * A195044 A195045 A195046 KEYWORD nonn,easy AUTHOR Omar E. Pol, Sep 27 2011 STATUS approved

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Last modified October 15 10:15 EDT 2019. Contains 328026 sequences. (Running on oeis4.)