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

Author

Vladimir Joseph Stephan Orlovsky, Jul 09 2010

Keywords

• sign
• easy

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

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

Crossrefs

Cf. A173142, A179297

Programs

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

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]