A220709 - cp's OEIS frontend

A220709 Number of ways to reciprocally link elements of a 4 X n array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links.

n	a(n)
1	1
2	1
3	5
4	13
5	37
6	105
7	298
8	846
9	2404
10	6826
11	19394
12	55081
13	156473
14	444445
15	1262497
16	3586113
17	10186570
18	28935186
19	82191652
20	233468038
21	663174914
22	1883771569
23	5350922525
24	15199487245
25	43174696525
26	122639283705
27	348361331050

[1, 1, 5, 13, 37, 105, 298, 846, 2404, 6826, 19394, 55081, 156473, 444445, 1262497, 3586113, 10186570, 28935186, 82191652, 233468038, 663174914, 1883771569, 5350922525, 15199487245, 43174696525, 122639283705, 348361331050]

cp's OEIS Frontend

A220709 Number of ways to reciprocally link elements of a 4 X n array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links.

Table of values

List of values