Number of unlabeled oriented edge-rooted 2-trees which have n triangles.

A303742

Number of unlabeled oriented edge-rooted 2-trees which have n triangles.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =2a(4) =7a(5) =18a(6) =68a(7) =251a(8) =1020a(9) =4258a(10) =18580a(11) =82716a(12) =377207a(13) =1748250a(14) =8227066a(15) =39197164a(16) =188824506a(17) =918333933a(18) =4504366940a(19) =22260929867a(20) =110763984273a(21) =554510459987

External references