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A131874
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Row sums of triangle A131873.
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1
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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
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..45.
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
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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
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EXAMPLE
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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).
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MATHEMATICA
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a[n_]:=Sum[7*i-10, {i, 1, n}]; [From Vladimir Joseph Stephan Orlovsky, Dec 04 2008]
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CROSSREFS
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Cf. A131873.
Sequence in context: A031107 A019557 A173107 * A111396 A080385 A120090
Adjacent sequences: A131871 A131872 A131873 * A131875 A131876 A131877
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KEYWORD
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nonn,easy
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AUTHOR
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Gary W. Adamson, Jul 22 2007
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EXTENSIONS
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More terms and Mathematica program from Orlovsky (4vladimir(AT)gmail.com), Dec 04 2008
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STATUS
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approved
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