%I #7 Mar 12 2018 20:14:34

%S 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,

%T 31,37,10,14,20,24,31,34,41,45,11,16,22,27,35,38,46,51,57,12,17,24,29,

%U 37,40,49,54,61,65,13,19,27,33,42,46,56,62,70,75,85

%N 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.

%C Same as A049687, but written as triangle.

%e The triangle starts:

%e 3

%e 4 5

%e 5 7 9

%e 6 8 11 13

%e 7 10 14 17 21

%e 8 11 15 18 23 25

%e 9 13 18 22 28 31 37

%e ...

%e T(3,2) = 7, X indicating hidden grid points:

%e 0-----1#####X#####X

%e | | | |

%e | | | |

%e 2-----3-----4-----5

%e # | # | |

%e # | # | |

%e X-----6-----X-----7

%Y Cf. A049687, A049691 (diagonal of triangle).

%K nonn,tabl

%O 1,1

%A _Hugo Pfoertner_, Mar 12 2018