1,2

a(n)=(1/6)*(112*n^3-156*n^2+50*n)

Cf. A100158, A100159 = alternate vertices; A100145 for more on structured numbers.

Sequence in context: A158067 A045220 A100158 this_sequence A100159 A100160 A010746

Adjacent sequences: A100163 A100164 A100165 this_sequence A100167 A100168 A100169

easy,nonn

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