A361240 Number of nonequivalent noncrossing triangular cacti with n triangles up to rotation and reflection.

1, 1, 1, 4, 19, 124, 931, 7801, 68685, 630850, 5966610, 57808920, 571178751, 5737672339, 58455577800, 602859484608, 6283968796705, 66119472527814, 701526880303315, 7498841163925819, 80696081185766970, 873654670250482120, 9510760874015305314, 104056578392127906720

Offset

0,4

Links

Andrew Howroyd, Table of n, a(n) for n = 0..500

Formula

a(2*n) = (A361237(2*n) + A002294(n))/2; a(2*n+1) = (A361237(2*n+1) + A118970(n))/2.

Crossrefs

Column 3 of A361239.

Cf. A002294, A118970, A361237.

Sequence in context: A094822 A280939 A121125 * A099953 A009324 A203236

Adjacent sequences: A361237 A361238 A361239 * A361241 A361242 A361243

Keyword

nonn

Author

Andrew Howroyd, Mar 06 2023

Status

approved