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 A172043 5n^2 - n + 1. 2
 1, 5, 19, 43, 77, 121, 175, 239, 313, 397, 491, 595, 709, 833, 967, 1111, 1265, 1429, 1603, 1787, 1981, 2185, 2399, 2623, 2857, 3101, 3355, 3619, 3893, 4177, 4471, 4775, 5089, 5413, 5747, 6091, 6445, 6809, 7183, 7567, 7961, 8365, 8779, 9203, 9637, 10081 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA G.f.: (1+2*x+7*x^2)/(1-x)^3. - Vincenzo Librandi, Jul 06 2012 a(n) = 3*a(n-1) -3*a(n-2) +a(n-3). - Vincenzo Librandi, Jul 06 2012 a(n) = 2*A005476(n)+1. - Bruno Berselli, Jul 06 2012 MATHEMATICA CoefficientList[Series[(7*x^2+2*x+1)/(1-x)^3, {x, 0, 40}], x] (* Vincenzo Librandi, Jul 06 2012 *) PROG (MAGMA) [ 5*n^2-n+1: n in [0..50] ]; (PARI) a(n)=5*n^2-n+1 \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Sequence in context: A022267 A094465 A020580 * A146616 A146395 A154302 Adjacent sequences:  A172040 A172041 A172042 * A172044 A172045 A172046 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Jan 29 2010 EXTENSIONS Replaced definition with formula. - N. J. A. Sloane, Mar 03 2010 STATUS approved

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