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 A022270 a(n) = n*(13*n - 1)/2. 3
 0, 6, 25, 57, 102, 160, 231, 315, 412, 522, 645, 781, 930, 1092, 1267, 1455, 1656, 1870, 2097, 2337, 2590, 2856, 3135, 3427, 3732, 4050, 4381, 4725, 5082, 5452, 5835, 6231, 6640, 7062, 7497, 7945, 8406, 8880, 9367, 9867, 10380, 10906, 11445 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..5000 Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) = 13*n + a(n-1) - 7 for n>0, a(0)=0. - Vincenzo Librandi, Aug 04 2010 a(0)=0, a(1)=6, a(2)=25; for n>2, a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Harvey P. Dale, Dec 02 2011 G.f.: x*(6 + 7*x)/(1 - x)^3. - Vincenzo Librandi, Mar 31 2015 a(n) = A022271(-n). - Bruno Berselli, Mar 31 2015 a(n) = A000217(7*n-1) - A000217(6*n-1). - Bruno Berselli, Oct 17 2016 E.g.f.: (x/2)*(13*x + 12)*exp(x). - G. C. Greubel, Aug 23 2017 MATHEMATICA Table[n (13 n - 1)/2, {n, 0, 40}] (* or *) LinearRecurrence[{3, -3, 1}, {0, 6, 25}, 40] (* Harvey P. Dale, Dec 02 2011 *) CoefficientList[Series[x (6 + 7 x) / (1 - x)^3, {x, 0, 40}], x] (* Vincenzo Librandi, Mar 31 2015 *) PROG (PARI) A022270(n) = n*(13*n-1)/2 \\ Michael B. Porter, Mar 12 2010 (MAGMA) [n*(13*n - 1)/2: n in [0..45]]; // Vincenzo Librandi, Mar 31 2015 CROSSREFS Cf. A000217, A022271. Cf. similar sequences listed in A022288. Sequence in context: A042185 A065069 A319429 * A001664 A255687 A096958 Adjacent sequences:  A022267 A022268 A022269 * A022271 A022272 A022273 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms from Vincenzo Librandi, Mar 31 2015 STATUS approved

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Last modified January 22 07:39 EST 2020. Contains 331139 sequences. (Running on oeis4.)