1,2

a(n)=(1/6)*(8*n^3-6*n^2+4*n)

Cf. A000578 = alternate vertex; A000447 = structured diamonds; A100145 for more on structured numbers.

Sequence in context: A034167 A093809 A037157 this_sequence A106113 A028419 A046664

Adjacent sequences: A100175 A100176 A100177 this_sequence A100179 A100180 A100181

easy,nonn

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