Number of n X n symmetric binary arrays with rows, considered as binary numbers, in nondecreasing order, and all but the outermost 2 rows or columns zero.

A162028

Number of n X n symmetric binary arrays with rows, considered as binary numbers, in nondecreasing order, and all but the outermost 2 rows or columns zero.

Terms

    a(0) =86a(1) =393a(2) =1319a(3) =4133a(4) =12139a(5) =33357a(6) =85798a(7) =207283a(8) =472758a(9) =1023449a(10) =2114041a(11) =4186441a(12) =7981693a(13) =14705357a(14) =26266256a(15) =45614055a(16) =77207792a(17) =127655369a(18) =206573275a(19) =327726605a(20) =510521919a(21) =781939821a(22) =1179010506a(23) =1751954107a(24) =2568128666

External references