Number of matchings in the n-web graph.

Terms

a(0) =4a(1) =3a(2) =23a(3) =93a(4) =439a(5) =1988a(6) =9107a(7) =41583a(8) =190047a(9) =868341a(10) =3967828a(11) =18130335a(12) =82844095a(13) =378544117a(14) =1729703523a(15) =7903633148a(16) =36114524127a(17) =165020163823a(18) =754036089983