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

1,2

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.

Links

Table of n, a(n) for n=1..20.

Crossrefs

Cf. A141226.

Sequence in context: A119973 A279229 A339963 * A026068 A217263 A330441

Adjacent sequences: A141246 A141247 A141248 * A141250 A141251 A141252

Keyword

nonn

Author

T. D. Noe, Jun 17 2008

Status

approved