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Number of nodes in the ordered rooted tree with binary encoding A014486(n).
2

%I #11 Nov 22 2022 11:57:52

%S 1,2,3,3,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,

%T 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,

%U 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7

%N Number of nodes in the ordered rooted tree with binary encoding A014486(n).

%C The binary encoding of an ordered tree (A014486) is obtained by replacing the internal left and right brackets with 0's and 1's, thus forming a binary number.

%F a(n) = A072643(n) + 1.

%e The first few rooted trees in binary encoding are:

%e 0: o

%e 2: (o)

%e 10: (oo)

%e 12: ((o))

%e 42: (ooo)

%e 44: (o(o))

%e 50: ((o)o)

%e 52: ((oo))

%e 56: (((o)))

%e 170: (oooo)

%e 172: (oo(o))

%e 178: (o(o)o)

%e 180: (o(oo))

%e 184: (o((o)))

%t binbalQ[n_]:=n==0||Count[IntegerDigits[n,2],0]==Count[IntegerDigits[n,2],1]&&And@@Table[Count[Take[IntegerDigits[n,2],k],0]<=Count[Take[IntegerDigits[n,2],k],1],{k,IntegerLength[n,2]}];

%t bint[n_]:=If[n==0,{},ToExpression[StringReplace[StringReplace[ToString[IntegerDigits[n,2]/.{1->"{",0->"}"}],","->""],"} {"->"},{"]]];

%t Table[Count[bint[k],_,{0,Infinity}],{k,Select[Range[0,10000],binbalQ]}]

%Y Run-lengths are A000108.

%Y Binary encodings are listed by A014486.

%Y Leaves of the ordered tree are counted by A057514, standard A358371.

%Y Branches of the ordered tree are counted by A057515.

%Y Edges of the ordered tree are counted by A072643.

%Y The Matula-Goebel number of the ordered tree is A127301.

%Y For standard instead of binary encoding we have A358372.

%Y The standard ranking of the ordered tree is A358523.

%Y Depth of the ordered tree is A358550, standard A358379.

%Y Cf. A000081, A001263, A057122, A358373, A358505, A358524.

%K nonn

%O 1,2

%A _Gus Wiseman_, Nov 22 2022