A179298 a(n)=n^3-(n-1)^3-(n-2)^3-...-1.

1, 7, 18, 28, 25, -9, -98, -272, -567, -1025, -1694, -2628, -3887, -5537, -7650, -10304, -13583, -17577, -22382, -28100, -34839, -42713, -51842, -62352, -74375, -88049, -103518, -120932, -140447, -162225, -186434, -213248, -242847, -275417

Offset

1,2

Comments

1^3-0=1, 2^3-1=7, 3^3-2^3-1=18, 4^3-3^3-2^3-1=28, 5^3-4^3-3^3-2^3-1=25, 6^3-5^3-4^3-3^3-2^3-1=-9,..

Links

Table of n, a(n) for n=1..34.

Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

Formula

a(n) = -n^2*(1-6*n+n^2)/4. G.f.: (2*x-1)*(x^2+4*x+1)/(x-1)^5. [From R. J. Mathar, Jul 11 2010]

Mathematica

f[n_]:=Module[{k=n-1, x=n^3}, While[k>0, x-=k^3; k--; ]; x]; lst={}; Do[AppendTo[lst, f[n]], {n, 5!}]; lst

Crossrefs

Cf. A173142, A179297

Sequence in context: A101865 A138391 A242293 * A144175 A017473 A131191

Adjacent sequences: A179295 A179296 A179297 * A179299 A179300 A179301

Keyword

sign,easy

Author

Vladimir Joseph Stephan Orlovsky, Jul 09 2010

Status

approved