OFFSET
1,4
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..200
FORMULA
EXAMPLE
The a(1) = 1 through a(6) = 13 trees:
o (o) (oo) (ooo) (oooo) (ooooo)
((oo)) ((ooo)) ((oooo))
(o(o)) (o(oo)) (o(ooo))
(oo(o)) (oo(oo))
(ooo(o))
(((ooo)))
((o)(oo))
((o(oo)))
((oo(o)))
(o((oo)))
(o(o)(o))
(o(o(o)))
(oo((o)))
MATHEMATICA
art[n_]:=If[n==1, {{}}, Join@@Table[Select[Tuples[art/@c], OrderedQ], {c, Join@@Permutations/@IntegerPartitions[n-1]}]];
Table[Length[Select[art[n], Count[#, {}, {0, Infinity}]>=Count[#, _[__], {0, Infinity}]&]], {n, 1, 10}]
PROG
(PARI) \\ See A358584 for R(n).
seq(n) = {my(A=R(n)); vector(n, n, my(u=Vecrev(A[n]/y)); vecsum(u[(n-1)\2+1..#u]))} \\ Andrew Howroyd, Dec 31 2022
CROSSREFS
The strict case is A358581.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 23 2022
EXTENSIONS
Terms a(19) and beyond from Andrew Howroyd, Dec 31 2022
STATUS
approved