A232222 Number of connected matchings with n crossings, in a disk.

1, 3, 13, 65, 354, 2035, 12151, 74618, 468233, 2989093, 19350384, 126730636, 838161358, 5589998777, 37552863737, 253877488505, 1725951649616, 11791929640102, 80921655496164, 557538161292336, 3855215134210479, 26745074320086283, 186095529221819237, 1298423607303399905

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

V. Pilaud, J. Rué, Analytic combinatorics of chord and hyperchord diagrams with k crossings, arXiv preprint arXiv:1307.6440, 2013.

Prog

(PARI) {my(A=T(20)); vector(#A, i, vecsum(A[i]))} \\ T(n) defined in A232223. - Andrew Howroyd, Nov 22 2024

Crossrefs

Row sums of A232223.

Cf. A000699.

Sequence in context: A364473 A186577 A141342 * A241598 A155867 A378257

Adjacent sequences: A232219 A232220 A232221 * A232223 A232224 A232225

Keyword

nonn

Author

N. J. A. Sloane, Nov 22 2013

Extensions

a(11) onwards from Andrew Howroyd, Nov 22 2024

Status

approved