A121639 - cp's OEIS frontend

A121639 Number of 2-cell columns in all deco polyominoes of height n. A deco polyomino is a directed column-convex polyomino in which the height, measured along the diagonal, is attained only in the last column.

n	a(n)
1	0
2	1
3	5
4	25
5	147
6	996
7	7668
8	66264
9	635976
10	6717600
11	77482080
12	969338880
13	13076778240
14	189261999360
15	2925629280000
16	48111515827200
17	838731380659200
18	15451544605593600
19	299960798422118400
20	6120505381423104000

[0, 1, 5, 25, 147, 996, 7668, 66264, 635976, 6717600, 77482080, 969338880, 13076778240, 189261999360, 2925629280000, 48111515827200, 838731380659200, 15451544605593600, 299960798422118400, 6120505381423104000]

cp's OEIS Frontend

A121639 Number of 2-cell columns in all deco polyominoes of height n. A deco polyomino is a directed column-convex polyomino in which the height, measured along the diagonal, is attained only in the last column.

Table of values

List of values