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A091468
Number of unlabeled alternating octupi with n black nodes and n white nodes.
1
1, 4, 10, 28, 76, 238, 736, 2428, 8110, 27754, 96196, 338158, 1200070, 4298578, 15511810, 56352508, 205906432, 756265486, 2790415564, 10338503578, 38446991530, 143461341082, 536962873540, 2015475400942, 7584636386326
OFFSET
1,2
FORMULA
3*A003239(n) - 2 (conjectured). - Ralf Stephan, Feb 06 2004
CROSSREFS
Main diagonal of A091467.
Sequence in context: A121302 A026150 A026123 * A103457 A083587 A228403
KEYWORD
nonn
AUTHOR
Christian G. Bower, Jan 12 2004
STATUS
approved