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A361241
Number of nonequivalent noncrossing 4-gonal cacti with n polygons up to rotation and reflection.
3
1, 1, 1, 6, 35, 349, 3766, 45632, 580203, 7687128, 104898024, 1466605630, 20916933674, 303368072539, 4463328542008, 66484512715040, 1001084180891355, 15217675702394661, 233285495922344929, 3603276856175739600, 56033315904277236728, 876698296980033411125
OFFSET
0,4
LINKS
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.
CROSSREFS
Column 4 of A361239.
Cf. A361238.
Sequence in context: A356494 A291595 A268139 * A051337 A267224 A192996
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Mar 06 2023
STATUS
approved