Number of non-isomorphic 4 X 4 nonnegative integer symmetric matrices with all row and column sums equal to n up to permutations of rows and columns.

A333886

Number of non-isomorphic 4 X 4 nonnegative integer symmetric matrices with all row and column sums equal to n up to permutations of rows and columns.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =12a(4) =33a(5) =74a(6) =163a(7) =319a(8) =596a(9) =1044a(10) =1754a(11) =2820a(12) =4394a(13) =6629a(14) =9756a(15) =14018a(16) =19743a(17) =27286a(18) =37111a(19) =49707a(20) =65699a(21) =85756a(22) =110691a(23) =141382a(24) =178882a(25) =224309a(26) =278990a(27) =344342a(28) =422000a(29) =513718

External references