Number of n X n binary arrays, symmetric about the diagonal and under 90-degree rotation, with every 1 adjacent to at least one other 1 both bishopwise and rookwise but with no three 1s in a row bishopwise or rookwise.

A144241

Number of n X n binary arrays, symmetric about the diagonal and under 90-degree rotation, with every 1 adjacent to at least one other 1 both bishopwise and rookwise but with no three 1s in a row bishopwise or rookwise.

Terms

    a(0) =1a(1) =2a(2) =1a(3) =3a(4) =2a(5) =4a(6) =4a(7) =13a(8) =10a(9) =65a(10) =30a(11) =231a(12) =168a(13) =1370a(14) =1317a(15) =17525a(16) =10846a(17) =191939a(18) =133498a(19) =2802218a(20) =2431795a(21) =73051050a(22) =54458173a(23) =2202863847a(24) =1575946900a(25) =84041510893a(26) =69906212126

External references