A266305 - cp's OEIS frontend

A266305 Number of n X n symmetric matrices with nonnegative integer entries and without zero rows or columns such that the sum of all entries is equal to 2n.

n	a(n)
0	1
1	1
2	7
3	74
4	1060
5	19013
6	408650
7	10219360
8	291158230
9	9302358947
10	329192040880
11	12775809098058
12	539351216354728
13	24600280965461923
14	1205263251360664310
15	63115789721408960624
16	3517483455875467926588
17	207834769804597591153769
18	12976002600530598793672490

[1, 1, 7, 74, 1060, 19013, 408650, 10219360, 291158230, 9302358947, 329192040880, 12775809098058, 539351216354728, 24600280965461923, 1205263251360664310, 63115789721408960624, 3517483455875467926588, 207834769804597591153769, 12976002600530598793672490]

cp's OEIS Frontend

A266305 Number of n X n symmetric matrices with nonnegative integer entries and without zero rows or columns such that the sum of all entries is equal to 2n.

Table of values

List of values