Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only either four adjacent vertically or four adjacent horizontally.

A145791

Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only either four adjacent vertically or four adjacent horizontally.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =3a(4) =1a(5) =6a(6) =1a(7) =17a(8) =26a(9) =113a(10) =318a(11) =1310a(12) =4072a(13) =21570a(14) =65328a(15) =442636a(16) =1558383a(17) =13750703a(18) =69409037a(19) =646392443a(20) =4686057331a(21) =48049954607a(22) =457665821401

External references