A369178 Irregular table read by rows: T(n,k) is the number of k-sided regions, k>=3, in a graph of n adjacent rectangles in a row with all possible diagonals drawn, as in A306302, but without the rectangles' edges which are perpendicular to the row.

2, 8, 4, 22, 14, 52, 34, 98, 82, 184, 146, 302, 268, 484, 426, 8, 710, 694, 4, 1064, 986, 8, 1498, 1436, 12, 2056, 1986, 12, 2710, 2780, 12, 3624, 3630, 24, 4682, 4728, 20, 6012, 5970, 24, 7518, 7628, 28, 9408, 9406, 32, 11526, 11702, 40, 14028, 14246, 64, 16782, 17330, 60

Offset

1,1

Comments

Unlike the graph in A306302, or the complete bipartite graph of order n, for n>=8 the graph contains regions with 5 edges. It is likely 5 is the maximum number of edges in any region for all n.

Links

Table of n, a(n) for n=1..55.

Scott R. Shannon, Image for n = 7.

Scott R. Shannon, Image for n = 8.

Formula

Sum of row(n) = A369175(n).

Example

The table begins:
2;
8, 4;
22, 14;
52, 34;
98, 82;
184, 146;
302, 268;
484, 426, 8;
710, 694, 4;
1064, 986, 8;
1498, 1436, 12;
2056, 1986, 12;
2710, 2780, 12;
3624, 3630, 24;
4682, 4728, 20;
6012, 5970, 24;
7518, 7628, 28;
9408, 9406, 32;
11526, 11702, 40;
14028, 14246, 64;
16782, 17330, 60;
20220, 20518, 68;
23998, 24468, 80;
28304, 28786, 84;
.
.

Crossrefs

Cf. A369175 (regions), A369176 (vertices), A369177 (edges), A306302, A324042, A324043, A368758.

Sequence in context: A264142 A088156 A019193 * A253884 A054788 A193851

Adjacent sequences: A369175 A369176 A369177 * A369179 A369180 A369181

Keyword

nonn,tabf

Author

Scott R. Shannon, Jan 15 2024

Status

approved