This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A300778 #7 Mar 12 2018 20:14:34 %S A300778 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 A300778 31,37,10,14,20,24,31,34,41,45,11,16,22,27,35,38,46,51,57,12,17,24,29, %U A300778 37,40,49,54,61,65,13,19,27,33,42,46,56,62,70,75,85 %N 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. %C A300778 Same as A049687, but written as triangle. %e A300778 The triangle starts: %e A300778 3 %e A300778 4 5 %e A300778 5 7 9 %e A300778 6 8 11 13 %e A300778 7 10 14 17 21 %e A300778 8 11 15 18 23 25 %e A300778 9 13 18 22 28 31 37 %e A300778 ... %e A300778 T(3,2) = 7, X indicating hidden grid points: %e A300778 0-----1#####X#####X %e A300778 | | | | %e A300778 | | | | %e A300778 2-----3-----4-----5 %e A300778 # | # | | %e A300778 # | # | | %e A300778 X-----6-----X-----7 %Y A300778 Cf. A049687, A049691 (diagonal of triangle). %K A300778 nonn,tabl %O A300778 1,1 %A A300778 _Hugo Pfoertner_, Mar 12 2018