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.

User: Wilf A. Wilson

Wilf A. Wilson's wiki page.

Wilf A. Wilson has authored 3 sequences.

A290289 The number of maximal subsemigroups of the monoid of partial orientation-preserving and reversing injective mappings on the set [1..n].

Original entry on oeis.org

2, 2, 5, 4, 7, 7, 10, 4, 5, 9, 14, 7, 16, 11, 11, 5, 19, 7, 22, 9, 13, 16, 26, 7, 8, 17, 6, 11, 32, 12, 35, 4, 16, 22, 15, 8, 40, 23, 19, 10, 44, 14, 47, 15, 11, 28, 50, 7, 10, 9, 23, 18, 56, 7, 19, 12, 25, 34, 62, 12, 65, 35, 13, 5
Offset: 1

Author

James Mitchell and Wilf A. Wilson, Jul 26 2017

Keywords

Crossrefs

Programs

  • Mathematica
    a[1] = a[2] = 2; a[n_] := PrimeNu[n-1] + DivisorSum[n, Identity, PrimeQ]+1; Array[a, 64] (* Jean-François Alcover, Feb 18 2019 *)

Formula

a(n)= A001221(n -1) + A008472(n) + 1, n > 2.

A290140 The number of maximal subsemigroups of the Jones monoid on the set [1..n].

Original entry on oeis.org

1, 2, 5, 9, 13, 19, 27, 39, 57, 85, 129, 199, 311, 491, 781, 1249, 2005, 3227, 5203, 8399, 13569, 21933, 35465, 57359, 92783, 150099, 242837, 392889, 635677, 1028515, 1664139, 2692599, 4356681, 7049221, 11405841, 18454999, 29860775, 48315707, 78176413
Offset: 1

Author

James Mitchell and Wilf A. Wilson, Jul 21 2017

Keywords

Comments

a(2n) is the number of maximal subsemigroups of the planar partition monoid of degree n.

Crossrefs

Cf. A000045.

Programs

  • Mathematica
    {1, 2}~Join~Table[2 Fibonacci[n - 1] + 2 n - 3, {n, 3, 39}] (* Michael De Vlieger, Jul 21 2017 *)
  • PARI
    Vec(x*(1 + x)*(1 - 2*x + 3*x^2 - 4*x^3 + x^4) / ((1 - x)^2*(1 - x - x^2)) + O(x^50)) \\ Colin Barker, Jul 21 2017

Formula

a(n) = 2 * A000045(n - 1) + 2n - 3, n > 2.
From Colin Barker, Jul 21 2017: (Start)
G.f.: x*(1 + x)*(1 - 2*x + 3*x^2 - 4*x^3 + x^4) / ((1 - x)^2*(1 - x - x^2)).
a(n) = -5 + (2^(-n)*((1-sqrt(5))^n*(1+sqrt(5)) + (-1+sqrt(5))*(1+sqrt(5))^n)) / sqrt(5) + 2*(1+n) for n>2.
a(n) = 3*a(n-1) - 2*a(n-2) - a(n-3) + a(n-4) for n>6.
(End)

A290138 Number of maximal subgroups of the symmetric group S_n.

Original entry on oeis.org

0, 1, 4, 8, 22, 53, 184, 353, 1376, 3977, 363904, 396498, 39920896, 40060127, 1543910, 4687418, 1307674433536, 1307902407753, 355687428358144, 355691118382364, 162615882312376736, 1267150213999727, 51090942171713634304, 51090956256672365547
Offset: 1

Author

James Mitchell and Wilf A. Wilson, Jul 21 2017

Keywords

Comments

a(n) + 1, n > 1, is the number of maximal subsemigroups of each of the following monoids of degree n: the full transformation monoid, the symmetric inverse monoid, the dual symmetric inverse monoid, the uniform block bijection monoid, and the Brauer monoid.
a(n) + 2 is the number of maximal subsemigroups of the partial transformation monoid of degree n.
a(n) + 3, n > 1, is the number of maximal subsemigroups of the partial Brauer monoid of degree n.
a(n) + 4, n > 1, is the number of maximal subsemigroups of the partition monoid of degree n.

Crossrefs

Cf. A066115.

Programs

  • GAP
    Sum(List(ConjugacyClassesMaximalSubgroups(SymmetricGroup(n)), Size));