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A059221 Number of 3-bead necklaces where each bead is an unlabeled rooted tree, by total number of nodes. 0
1, 1, 2, 4, 8, 18, 43, 103, 255, 642, 1640, 4242, 11096, 29278, 77882, 208589, 562056, 1522606, 4144521, 11329608, 31090910, 85618848, 236530942, 655344579, 1820585313, 5070138554, 14151907583, 39584395796, 110938500821, 311481097178 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..29.

CROSSREFS

See A058855 (the 6-bead analog) for details.

Sequence in context: A318797 A318850 A052327 * A193617 A233139 A308246

Adjacent sequences: A059218 A059219 A059220 * A059222 A059223 A059224

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jan 18 2001

STATUS

approved

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Last modified February 5 07:43 EST 2023. Contains 360082 sequences. (Running on oeis4.)