cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A358727 Matula-Goebel numbers of rooted trees with greater number of leaves (width) than node-height.

Original entry on oeis.org

8, 16, 24, 28, 32, 36, 38, 42, 48, 49, 53, 54, 56, 57, 63, 64, 72, 76, 80, 81, 84, 96, 98, 104, 106, 108, 112, 114, 120, 126, 128, 131, 133, 136, 140, 144, 147, 148, 152, 156, 159, 160, 162, 168, 171, 172, 178, 180, 182, 184, 189, 190, 192, 196, 200, 204, 208
Offset: 1

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Author

Gus Wiseman, Dec 01 2022

Keywords

Comments

The Matula-Goebel number of a rooted tree is the product of primes indexed by the Matula-Goebel numbers of the branches of its root, which gives a bijective correspondence between positive integers and unlabeled rooted trees.
Node-height is the number of nodes in the longest path from root to leaf.

Examples

			The terms together with their corresponding rooted trees begin:
   8: (ooo)
  16: (oooo)
  24: (ooo(o))
  28: (oo(oo))
  32: (ooooo)
  36: (oo(o)(o))
  38: (o(ooo))
  42: (o(o)(oo))
  48: (oooo(o))
  49: ((oo)(oo))
  53: ((oooo))
  54: (o(o)(o)(o))
  56: (ooo(oo))
  57: ((o)(ooo))
  63: ((o)(o)(oo))
  64: (oooooo)
  72: (ooo(o)(o))
  76: (oo(ooo))
		

Crossrefs

Positions of negative terms in A358726.
These trees are counted by A358728.
Differences: A358580, A358724, A358726, A358729.
A000081 counts rooted trees, ordered A000108.
A034781 counts rooted trees by nodes and height, ordered A080936.
A055277 counts rooted trees by nodes and leaves, ordered A001263.

Programs

  • Mathematica
    MGTree[n_]:=If[n==1,{},MGTree/@Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
    Select[Range[1000],Depth[MGTree[#]]-1