1,2

a(n)=(1/6)*(26*n^3-30*n^2+10*n)

Cf. A063523 = alternate vertex; A100188 = structured anti-diamonds; A100145 for more on structured numbers.

Sequence in context: A143666 A139757 A164603 this_sequence A039453 A063495 A039408

Adjacent sequences: A100184 A100185 A100186 this_sequence A100188 A100189 A100190

easy,nonn

James A. Record (james.record(AT)gmail.com). Nov 07, 2004.