A139673 Number of n X n symmetric binary matrices with all row sums 6.

1, 232, 66178, 24243520, 11234051976, 6549149852112, 4762109992158288, 4274712091685443584, 4686484162304929219950, 6209619146419137708859600, 9845751579221258486943505348, 18509102695712474753650903363840, 40904306737052771732376660591663712

Offset: 6

Author

R. H. Hardin, Jun 12 2008

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 6..25

Crossrefs

Column k=6 of A333157 and row 6 of A188448.

Extensions

Terms a(13) and beyond from Andrew Howroyd, Mar 09 2020