Number of oriented polygonal 2-trees with n oriented quadrilaterals.

A340813

Number of oriented polygonal 2-trees with n oriented quadrilaterals.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =3a(4) =11a(5) =49a(6) =252a(7) =1406a(8) =8405a(9) =52348a(10) =337029a(11) =2225333a(12) =15002763a(13) =102896407a(14) =716106077a(15) =5046649182a(16) =35956186581a(17) =258649116963

External references