Number of symmetric 0-1 (n+1) X (n+1) matrices with row sums 2 and first row starting 1,1 for n > 0, a(0)=1.

A001495

Number of symmetric 0-1 (n+1) X (n+1) matrices with row sums 2 and first row starting 1,1 for n > 0, a(0)=1.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =3a(4) =13a(5) =70a(6) =462a(7) =3592a(8) =32056a(9) =322626a(10) =3611890a(11) =44491654a(12) =597714474a(13) =8693651092a(14) =136059119332

External references