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

A091468

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

Terms

    a(0) =1a(1) =4a(2) =10a(3) =28a(4) =76a(5) =238a(6) =736a(7) =2428a(8) =8110a(9) =27754a(10) =96196a(11) =338158a(12) =1200070a(13) =4298578a(14) =15511810a(15) =56352508a(16) =205906432a(17) =756265486a(18) =2790415564a(19) =10338503578a(20) =38446991530a(21) =143461341082a(22) =536962873540

External references