A357420 - cp's OEIS frontend

A357420 a(n) is the hafnian of the 2n X 2n symmetric matrix defined by M[i,j] = abs(i - j) if min(i, j) < max(i, j) <= 2*min(i, j), and otherwise 0.

n	a(n)
0	1
1	1
2	1
3	8
4	86
5	878
6	13730
7	348760
8	11622396
9	509566864
10	26894616012
11	1701189027944
12	125492778658096
13	10738546182981256
14	1049631636279244832
15	117756049412699967072

[1, 1, 1, 8, 86, 878, 13730, 348760, 11622396, 509566864, 26894616012, 1701189027944, 125492778658096, 10738546182981256, 1049631636279244832, 117756049412699967072]

cp's OEIS Frontend

A357420 a(n) is the hafnian of the 2n X 2n symmetric matrix defined by M[i,j] = abs(i - j) if min(i, j) < max(i, j) <= 2*min(i, j), and otherwise 0.

Table of values

List of values