A026049 a(n) = dot_product(1,2,...,n)*(7,8,...,n,1,2,3,4,5,6).

119, 156, 204, 265, 341, 434, 546, 679, 835, 1016, 1224, 1461, 1729, 2030, 2366, 2739, 3151, 3604, 4100, 4641, 5229, 5866, 6554, 7295, 8091, 8944, 9856, 10829, 11865, 12966, 14134, 15371, 16679, 18060, 19516, 21049, 22661, 24354, 26130, 27991, 29939, 31976, 34104, 36325, 38641, 41054

Offset: 7

Author

Clark Kimberling

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 7..1000
• Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

Crossrefs

Column 6 of triangle A094414.

Programs

Magma

[n*(2*n^2-15*n+109)/6: n in [7..60]]; // Vincenzo Librandi, Oct 17 2013

Mathematica

CoefficientList[Series[(119 - 320 x + 294 x^2 - 91 x^3)/(1 - x)^4, {x, 0, 60}], x] (* Vincenzo Librandi, Oct 17 2013 *)

Formula

a(n) = n(2n^2-15n+109)/6. - Ralf Stephan, Apr 30 2004

G.f.: x^7*(119-320*x+294*x^2-91*x^3)/(1-x)^4. - Colin Barker, Sep 17 2012