A268949 Number of sequences in {1,...,2n}^(2n) with longest increasing subsequence of length n.

1, 3, 175, 23611, 5179791, 1583828620, 621893381187, 298289430051783, 169027530016448143, 110485582196129404780, 81829925127960010076736

Offset: 0

Author

Alois P. Heinz, Feb 16 2016

Keywords

• nonn

Examples

			a(1) = 3: 11, 21, 22.
a(2) = 175: 1112, 1113, 1114, 1121, ..., 4414, 4423, 4424, 4434.
		

Crossrefs

Cf. A245667.

Formula

a(n) = A245667(2n,n).