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

A138178

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

Terms

    a(0) =1a(1) =1a(2) =3a(3) =9a(4) =33a(5) =125a(6) =531a(7) =2349a(8) =11205a(9) =55589a(10) =291423a(11) =1583485a(12) =8985813a(13) =52661609a(14) =319898103a(15) =2000390153a(16) =12898434825a(17) =85374842121a(18) =580479540219

External references