A239072 - cp's OEIS frontend

A239072 Maximum number of cells in an n X n square grid that can be painted such that no two orthogonally adjacent cells are painted and every unpainted cell can be reached from the edge of the grid by a series of orthogonal steps to unpainted cells.

n	a(n)
0	0
1	1
2	2
3	5
4	7
5	11
6	15
7	21
8	26
9	32
10	39
11	47
12	55
13	64
14	74
15	85
16	95
17	107
18	119
19	132
20	146
21	160
22	175
23	191
24	207
25	224

[0, 1, 2, 5, 7, 11, 15, 21, 26, 32, 39, 47, 55, 64, 74, 85, 95, 107, 119, 132, 146, 160, 175, 191, 207, 224]