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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A246312 Decimal expansion of a constant related to identity matched trees.

Original entry on oeis.org

5, 2, 4, 9, 0, 3, 2, 4, 9, 1, 2, 2, 8, 1, 7, 0, 5, 7, 9, 1, 6, 4, 9, 5, 2, 2, 1, 6, 1, 8, 4, 3, 0, 9, 2, 6, 5, 3, 4, 3, 0, 8, 6, 3, 3, 7, 6, 4, 8, 7, 3, 6, 5, 0, 3, 2, 0, 2, 2, 3, 3, 1, 8, 6, 0, 5, 9, 5, 8, 5, 5, 6, 5, 2, 6, 4, 0, 2, 8, 7, 7, 5, 8, 7, 0, 4, 5, 7, 4, 4, 0, 9, 9, 4, 5, 1, 8, 6, 5, 4, 7, 3, 8, 7, 6
Offset: 1

Views

Author

Vaclav Kotesovec, Aug 25 2014

Keywords

Examples

			5.249032491228170579164952216184309265343086337648736503202233186059585565...

Crossrefs

Cf. A005753, A005754, A005755, A102755, A038078, A038077.

Formula

Equals lim n -> infinity A005753(n)^(1/n).
Equals lim n -> infinity A005754(n)^(1/n).
Equals lim n -> infinity A005755(n)^(1/n).
Equals lim n -> infinity A102755(n)^(1/n).
Equals lim n -> infinity A038078(n)^(1/n).

Extensions

More terms from Vaclav Kotesovec, Sep 06 2014, Feb 24 2015 and Dec 26 2020

A038077 Number of rooted identity trees with 2-colored nodes.

Original entry on oeis.org

2, 4, 10, 36, 132, 532, 2222, 9584, 42248, 189776, 864830, 3989656, 18593424, 87413444, 414060796, 1974260912, 9467922870, 45638482068, 221001289714, 1074591477112, 5244497440468, 25681907242416, 126149132242490, 621386729646752, 3068748094479108
Offset: 1

Views

Author

Christian G. Bower, Jan 04 1999

Keywords

Comments

Shifts left and halves under Weigh transform.

Links

Crossrefs

Cf. A004111, A038078, A038079, A038080, A246312.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
      add(binomial(a(i), j)*b(n-i*j, i-1), j=0..n/i)))
    end:
a:= n-> `if`(n=1, 2, 2*b((n-1)$2)):
seq(a(n), n=1..40); # Alois P. Heinz, May 20 2013
  • Mathematica
    b[n_, i_] := b[n, i] = If[n==0, 1, If[i<1, 0, Sum[Binomial[a[i], j]*b[n - i*j, i-1], {j, 0, n/i}]]];
a[n_] := If[n==1, 2, 2*b[n-1, n-1]];
Table[a[n], {n, 1, 40}] (* Jean-François Alcover, Mar 01 2016, after Alois P. Heinz *)

Formula

a(n) = 2 * A005753(n).
Showing 1-2 of 2 results.

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