1,7

Table of n, a(n) for n=1..18.

Three collinear points in an n X n grid A000938 ; n X n X n grid A157882

Sequence in context: A270537 A076581 A183675 * A194605 A233104 A071235

Adjacent sequences: A178269 A178270 A178271 * A178273 A178274 A178275

nonn

R. H. Hardin, suggested by R. J. Mathar in the Sequence Fans Mailing List, May 24 2010

approved