a(n) is 1/5 times the number of anti-chains of size four in "0,1,2" Motzkin trees on n edges.
A330966
a(n) is 1/5 times the number of anti-chains of size four in "0,1,2" Motzkin trees on n edges.
Terms
- a(0) =1a(1) =11a(2) =84a(3) =520a(4) =2835a(5) =14133a(6) =65960a(7) =292536a(8) =1245789a(9) =5132375a(10) =20569512a(11) =80541300a(12) =309143065a(13) =1166302239a(14) =4334300976a(15) =15895046840a(16) =57608669274a(17) =206606077758a(18) =733992204988
External references
- oeis: A330966