A141249 Numbers n such that the central point of the square n X n lattice sees the minimal number of points.

1, 21, 33, 45, 73, 81, 193, 201, 241, 273, 313, 381, 421, 445, 453, 661, 693, 861, 885, 913

Offset: 1

Author

T. D. Noe, Jun 17 2008

Keywords

• nonn

Comments

These n are the numbers for which A141248(n) is odd. Note that n must be odd. When A141248(n)=1, the central point is the only point seeing the minimal number of points. These numbers are 1 or 9 (mod 12). These numbers also seem to produce cubic n X n X n lattices in which the central point has minimal visibility. Note that for n>1, n+1 is twice a prime power in A141250.

Crossrefs

Cf. A141226.