A071902 Sum_{k=0..n^2} (k^2 - n^2)/n.

-1, 5, 65, 306, 975, 2479, 5425, 10660, 19311, 32825, 53009, 82070, 122655, 177891, 251425, 347464, 470815, 626925, 821921, 1062650, 1356719, 1712535, 2139345, 2647276, 3247375, 3951649, 4773105, 5725790, 6824831, 8086475, 9528129

Offset

1,2

Links

Table of n, a(n) for n=1..31.

Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).

Formula

a(n) = n*(2*n^2-5)*(n^2+1)/6. - Vladeta Jovovic, Jun 15 2002

G.f.: -x*(x^4-11*x^3-20*x^2-11*x+1) / (x-1)^6. - Colin Barker, Sep 29 2014

Prog

(PARI) vector(100, n, sum(k=0, n^2, k^2-n^2)/n) \\ Colin Barker, Sep 29 2014

Crossrefs

Cf. A052459.

Sequence in context: A126955 A091105 A234335 * A211412 A052199 A093195

Adjacent sequences: A071899 A071900 A071901 * A071903 A071904 A071905

Keyword

sign,easy

Author

Robert G. Wilson v, Jun 12 2002

Status

approved