Total number of two-element anti-chains over all ordered trees on n edges.

A139262

Total number of two-element anti-chains over all ordered trees on n edges.

Terms

    a(0) =0a(1) =0a(2) =1a(3) =8a(4) =47a(5) =244a(6) =1186a(7) =5536a(8) =25147a(9) =112028a(10) =491870a(11) =2135440a(12) =9188406a(13) =39249768a(14) =166656772a(15) =704069248a(16) =2961699667a(17) =12412521388a(18) =51854046982a(19) =216013684528a(20) =897632738722

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