A140422 - cp's OEIS frontend

A140422 Half the number of n X n symmetric binary matrices with every 1 adjacent to some 0 horizontally or vertically and every 0 adjacent to some 1 horizontally or vertically.

n	a(n)
2	1
3	5
4	47
5	849
6	29241
7	1901849
8	234932757
9	55047807551
10	24470603864937
11	20637055514911557
12	33018065501295740951
13	100220335496292824426843
14	577112450349963078523926227

[1, 5, 47, 849, 29241, 1901849, 234932757, 55047807551, 24470603864937, 20637055514911557, 33018065501295740951, 100220335496292824426843, 577112450349963078523926227]

cp's OEIS Frontend

A140422 Half the number of n X n symmetric binary matrices with every 1 adjacent to some 0 horizontally or vertically and every 0 adjacent to some 1 horizontally or vertically.

Table of values

List of values