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A361240
Number of nonequivalent noncrossing triangular cacti with n triangles up to rotation and reflection.
3
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
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.
Sequence in context: A094822 A280939 A121125 * A377967 A099953 A009324
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Mar 06 2023
STATUS
approved