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 A131874 (7n^2 + 15n + 2) / 2. 2
 1, 12, 30, 55, 87, 126, 172, 225, 285, 352, 426, 507, 595, 690, 792, 901, 1017, 1140, 1270, 1407, 1551, 1702, 1860, 2025, 2197, 2376, 2562, 2755, 2955, 3162, 3376, 3597, 3825, 4060, 4302, 4551, 4807, 5070, 5340, 5617, 5901, 6192, 6490, 6795, 7107, 7426 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Row sums of triangle A131873. LINKS Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA Binomial transform of (1, 11, 7, 0, 0, 0,...). a(n) = a(n-1) + 7*n + 4, (with a(0)=1). - Vincenzo Librandi, Nov 23 2010 a(n) = (2 + 15*n + 7*n^2)/2; a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3); G.f.: (1+9*x-3*x^2)/ (1-x)^3. - Colin Barker, Sep 13 2012 EXAMPLE a(2) = 30 = sum of row 2 terms of triangle A131873: (15 + 8 + 7). a(2) = 30 = (1, 2, 1) dot (1, 11, 7) = (1 + 22 + 7). MAPLE A131874:=n->(2+15*n+7*n^2)/2; seq(A131874(n), n=0..100); # Wesley Ivan Hurt, Mar 26 2014 MATHEMATICA a[n_] := Sum[7*i-10, {i, n}]; Table[a[n], {n, 40]] (* Vladimir Joseph Stephan Orlovsky, Dec 04 2008 *) PROG (PARI) a(n)=(7*n^2+15*n+2)/2 \\ Charles R Greathouse IV, Jun 16 2017 CROSSREFS Cf. A131873. Sequence in context: A019557 A173107 A277978 * A111396 A080385 A120090 Adjacent sequences:  A131871 A131872 A131873 * A131875 A131876 A131877 KEYWORD nonn,easy AUTHOR Gary W. Adamson, Jul 22 2007 EXTENSIONS More terms from Vladimir Joseph Stephan Orlovsky, Dec 04 2008 STATUS approved

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