A139010 Number of n X n symmetric binary matrices containing no more than two 1s in any 3 X 3 sub-block.

1, 2, 5, 10, 46, 298, 1984, 21540, 331078, 6336017, 173488605, 6651795802, 340061007958, 23986915555236, 2342976613039703, 311875652121439248, 56925380854171209808, 14298682300093479646164, 4921580523122987792169589