A252823 - cp's OEIS frontend

A252823 Number of n X 3 nonnegative integer arrays with upper left 0 and every value within 3 of its city block distance from the upper left and every value increasing by 0 or 1 with every step right or down.

n	a(n)
1	4
2	18
3	81
4	340
5	1238
6	3891
7	10761
8	26764
9	60988
10	129236
11	257653
12	487744
13	883142
14	1538541
15	2591269
16	4236040
17	6743492
18	10483190
19	15951849
20	23807612
21	34911302
22	50375655
23	71623633
24	100457012
25	139136540
26	190475064
27	257945133
28	345802696

[4, 18, 81, 340, 1238, 3891, 10761, 26764, 60988, 129236, 257653, 487744, 883142, 1538541, 2591269, 4236040, 6743492, 10483190, 15951849, 23807612, 34911302, 50375655, 71623633, 100457012, 139136540, 190475064, 257945133, 345802696]

cp's OEIS Frontend

A252823 Number of n X 3 nonnegative integer arrays with upper left 0 and every value within 3 of its city block distance from the upper left and every value increasing by 0 or 1 with every step right or down.

Table of values

List of values