2,2

n[ (n-1)/2 ]

a(n)=a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5). G.f.: -x^3*(3+x)/((1+x)^2*(x-1)^3). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 08 2009]

Sequence in context: A131179 A079353 A135116 this_sequence A101506 A092434 A031367

Adjacent sequences: A050184 A050185 A050186 this_sequence A050188 A050189 A050190

nonn

Clark Kimberling (ck6(AT)evansville.edu)