A361241 Number of nonequivalent noncrossing 4-gonal cacti with n polygons up to rotation and reflection.

1, 1, 1, 6, 35, 349, 3766, 45632, 580203, 7687128, 104898024, 1466605630, 20916933674, 303368072539, 4463328542008, 66484512715040, 1001084180891355, 15217675702394661, 233285495922344929, 3603276856175739600, 56033315904277236728, 876698296980033411125

Offset: 0

Author

Andrew Howroyd, Mar 06 2023

Keywords

• nonn

Links

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

Crossrefs

Column 4 of A361239.

Cf. A361238.

Formula

a(2*n) = (A361238(2*n) + binomial(7*n + 1, n)/(7*n + 1))/2; a(2*n+1) = (A361238(2*n+1) + 4*binomial(7*n + 4, n)/(7*n + 4))/2.