A091468 Number of unlabeled alternating octopuses with n black nodes and n white nodes.

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

Author

Christian G. Bower, Jan 12 2004

Keywords

• nonn
• changed

Crossrefs

Main diagonal of A091467.

Formula

3*A003239(n) - 2 (conjectured). - Ralf Stephan, Feb 06 2004