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.

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A060148 Number of closed forest meander systems with 2n crossings.

Original entry on oeis.org

1, 1, 3, 15, 97, 733, 6147, 55541, 530773, 5298723, 54780831, 582817337, 6350647873, 70614662303, 798935833885, 9176290300419, 106793746090045, 1257408517909283, 14958873368871405, 179614516459970349, 2174717049372338913, 26530091641879493297, 325875790867387681293
Offset: 0

Views

Author

N. J. A. Sloane, Apr 10 2001

Keywords

Comments

A forest meander system is a meander system that does not have any components which are entirely enclosed by another. - Andrew Howroyd, Nov 22 2015
The components of a forest meander system do not necessarily all have exterior arches. See example. Those that do are called tame (A060066). - Andrew Howroyd, Feb 02 2025

Examples

			An example of a 2 component forest meander system with 8 crossings that is not tame:
      ________
     / ______ \
    / /      \ \
   / / /\  /\ \ \
   \ \ \/ / /  \/
    \ \__/ /
     \____/

Links

Crossrefs

Row sums of A380368.
Meander sequences in Bacher's paper: A005315, A060066, A060089, A060111, A060148, A060149, A060174, A060198, A060206.

Formula

1 <= A060066(n) <= a(n) <= A060174(n) <= A060198(n) <= 16^n. - Andrew Howroyd, Feb 02 2025

Extensions

More terms from Sascha Kurz, Mar 25 2002
a(15)-a(20) from Andrew Howroyd, Nov 22 2015
a(0)=1 prepended and a(21)-a(22) from Andrew Howroyd, Jan 31 2025
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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