A300778 Number of grid points visible from a corner of an m X n rectangular region on a square grid written as triangle T(m,n), 1 <= n <= m.

3, 4, 5, 5, 7, 9, 6, 8, 11, 13, 7, 10, 14, 17, 21, 8, 11, 15, 18, 23, 25, 9, 13, 18, 22, 28, 31, 37, 10, 14, 20, 24, 31, 34, 41, 45, 11, 16, 22, 27, 35, 38, 46, 51, 57, 12, 17, 24, 29, 37, 40, 49, 54, 61, 65, 13, 19, 27, 33, 42, 46, 56, 62, 70, 75, 85

Offset: 1

Author

Hugo Pfoertner, Mar 12 2018

Keywords

• nonn
• tabl

Comments

Same as A049687, but written as triangle.

Examples

			The triangle starts:
  3
  4   5
  5   7   9
  6   8  11  13
  7  10  14  17  21
  8  11  15  18  23  25
  9  13  18  22  28  31  37
  ...
T(3,2) = 7, X indicating hidden grid points:
  0-----1#####X#####X
  |     |     |     |
  |     |     |     |
  2-----3-----4-----5
  #     | #   |     |
  #     |   # |     |
  X-----6-----X-----7
		

Crossrefs

Cf. A049687, A049691 (diagonal of triangle).