A220634 - cp's OEIS frontend

A220634 Number of ways to reciprocally link elements of an 4 X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.

n	a(n)
1	1
2	1
3	5
4	37
5	257
6	1665
7	10695
8	68637
9	440509
10	2827377
11	18148003
12	116487861
13	747713321
14	4799439985
15	30806785967
16	197743565181
17	1269282762917
18	8147313444929
19	52296241209451
20	335680820572405
21	2154679016567857

[1, 1, 5, 37, 257, 1665, 10695, 68637, 440509, 2827377, 18148003, 116487861, 747713321, 4799439985, 30806785967, 197743565181, 1269282762917, 8147313444929, 52296241209451, 335680820572405, 2154679016567857]

cp's OEIS Frontend

A220634 Number of ways to reciprocally link elements of an 4 X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.

Table of values

List of values