A279679 - OEIS

%I #14 Dec 24 2016 11:19:36

%S 0,0,0,1,0,1,1,2,0,2,3,4,2,3,4,5,0,3,4,5,6,7,3,4,5,6,7,8,9,10,0,4,6,7,

%T 8,9,10,11,12,13,4,5,7,8,9,10,11,12,13,14,15,16,0,5,8,9,10,11,12,13,

%U 14,15,16,17,18,19,20

%N Irregular triangle read by rows: possible numbers of diagonals of an n-edged convex polyhedron.

%C The beginning of the irregular triangle is:

%C 6  | 0;

%C 7  | -

%C 8  | 0;

%C 9  | 0, 1;

%C 10 | 0, 1;

%C 11 | 1, 2;

%C 12 | 0, 2, 3, 4;

%C 13 | 2, 3, 4, 5;

%C 14 | 0, 3, 4, 5,  6,  7;

%C 15 | 3, 4, 5, 6,  7,  8,  9, 10;

%C 16 | 0, 4, 6, 7,  8,  9, 10, 11, 12, 13;

%C 17 | 4, 5, 7, 8,  9, 10, 11, 12, 13, 14, 15, 16;

%C 18 | 0, 5, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20;

%Y Cf. A279015, A279019, A279022, A279620, A279647, A279681.

%K nonn,tabf

%O 6,8

%A _Vladimir Letsko_, Dec 16 2016