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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A289147 Number of (n+1) X (n+1) binary matrices M with at most one 1 in each of the first n rows and each of the first n columns and M[n+1,n+1] = 0.

Original entry on oeis.org

1, 5, 34, 286, 2840, 32344, 414160, 5876336, 91356544, 1542401920, 28075364096, 547643910400, 11389266525184, 251428006132736, 5869482147358720, 144413021660821504, 3733822274973040640, 101181690628832198656, 2867011297057247002624, 84764595415605494743040
Offset: 0

Views

Author

Alois P. Heinz, Jun 26 2017

Keywords

Comments

Number of marriage patterns between a labeled set X of n women and a labeled set Y of n men (all heterosexual): some couples can be formed where one partner is from X and the other from Y, some members of X and Y marry external (unlabeled) partners, and some do not marry.

Examples

			a(1) = 5:
[0 0]  [1 0]  [0 1]  [0 0]  [0 1]
[0 0]  [0 0]  [0 0]  [1 0]  [1 0] .
.
a(2) = 34:
[0 0 0]  [0 0 0]  [0 0 0]  [0 0 0]  [0 0 0]  [0 0 0]  [0 0 0]
[0 0 0]  [0 0 0]  [0 0 0]  [0 0 0]  [0 0 1]  [0 0 1]  [0 0 1]
[0 0 0]  [0 1 0]  [1 0 0]  [1 1 0]  [0 0 0]  [0 1 0]  [1 0 0]
.
[0 0 0]  [0 0 0]  [0 0 0]  [0 0 0]  [0 0 0]  [0 0 1]  [0 0 1]
[0 0 1]  [0 1 0]  [0 1 0]  [1 0 0]  [1 0 0]  [0 0 0]  [0 0 0]
[1 1 0]  [0 0 0]  [1 0 0]  [0 0 0]  [0 1 0]  [0 0 0]  [0 1 0]
.
[0 0 1]  [0 0 1]  [0 0 1]  [0 0 1]  [0 0 1]  [0 0 1]  [0 0 1]
[0 0 0]  [0 0 0]  [0 0 1]  [0 0 1]  [0 0 1]  [0 0 1]  [0 1 0]
[1 0 0]  [1 1 0]  [0 0 0]  [0 1 0]  [1 0 0]  [1 1 0]  [0 0 0]
.
[0 0 1]  [0 0 1]  [0 0 1]  [0 1 0]  [0 1 0]  [0 1 0]  [0 1 0]
[0 1 0]  [1 0 0]  [1 0 0]  [0 0 0]  [0 0 0]  [0 0 1]  [0 0 1]
[1 0 0]  [0 0 0]  [0 1 0]  [0 0 0]  [1 0 0]  [0 0 0]  [1 0 0]
.
[0 1 0]  [1 0 0]  [1 0 0]  [1 0 0]  [1 0 0]  [1 0 0]
[1 0 0]  [0 0 0]  [0 0 0]  [0 0 1]  [0 0 1]  [0 1 0]
[0 0 0]  [0 0 0]  [0 1 0]  [0 0 0]  [0 1 0]  [0 0 0]  .
		

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<2, 4*n+1,
          (2*n+3)*a(n-1)-(n-1)^2*a(n-2))
        end:
    seq(a(n), n=0..25);
    # second Maple program:
    a:= n-> n-> n! * add(binomial(n, i)*4^i/i!, i=0..n):
    seq(a(n), n=0..25);
    # third Maple program:
    a:= n-> n!* simplify(LaguerreL(n, -4), 'LaguerreL'):
    seq(a(n), n=0..25);
  • Mathematica
    Table[n! LaguerreL[n, -4], {n, 0, 30}] (* Indranil Ghosh, Jul 06 2017 *)
  • Python
    from mpmath import *
    mp.dps=150
    l=chop(taylor(lambda x:exp(4*x/(1-x))/(1-x), 0, 31))
    print([int(fac(i)*l[i]) for i in range(len(l))]) # Indranil Ghosh, Jul 06 2017
    # or #
    from mpmath import *
    mp.dps=100
    def a(n): return int(fac(n)*laguerre(n, 0, -4))
    print([a(n) for n in range(31)]) # Indranil Ghosh, Jul 06 2017

Formula

E.g.f.: exp(4*x/(1-x))/(1-x).
a(n) = Sum_{i=0..n} i! * (2^(n-i)*binomial(n,i))^2.
a(n) = Sum_{i=0..n} (n-i)! * 4^i * binomial(n,i)^2.
a(n) = n! * Sum_{i=0..n} 4^i/i! * binomial(n,i).
a(n) = (2*n+3)*a(n-1)-(n-1)^2*a(n-2) for n>=2, a(n) = 4*n+1 for n<2.
a(n) = n! * Laguerre(n,-4) = n! * A160611(n)/A160612(n).
a(n) ~ exp(-2 + 4*sqrt(n) - n) * n^(n + 1/4) / 2 * (1 + 163/(96*sqrt(n))). - Vaclav Kotesovec, Nov 13 2017
Sum_{n>=0} a(n) * x^n / (n!)^2 = exp(x) * Sum_{n>=0} 4^n * x^n / (n!)^2. - Ilya Gutkovskiy, Jul 17 2020

A160611 Numerator of Laguerre(n, -4).

Original entry on oeis.org

1, 5, 17, 143, 355, 4043, 5177, 367271, 713723, 2410003, 109669391, 85569361, 11122330591, 245535162239, 52108328723, 70514170732823, 1753034045867, 3087820148584967, 3365163124738543, 15216530369586809, 9955926989110451149, 63735241273696485041
Offset: 0

Views

Author

N. J. A. Sloane, Nov 14 2009

Keywords

Crossrefs

For denominators see A160612.
Cf. A289147.

Programs

  • Magma
    [Numerator((&+[Binomial(n,k)*(4^k/Factorial(k)): k in [0..n]])): n in [0..30]]; // G. C. Greubel, May 12 2018
  • Mathematica
    Numerator[Table[LaguerreL[n, -4], {n, 0, 50}]] (* G. C. Greubel, May 12 2018 *)
  • PARI
    for(n=0,30, print1(numerator(sum(k=0,n, binomial(n,k)*(4^k/k!))), ", ")) \\ G. C. Greubel, May 12 2018
    
  • PARI
    a(n) = numerator(pollaguerre(n, 0, -4)); \\ Michel Marcus, Feb 05 2021
    

Formula

a:= n-> numer(add(binomial(n, i)*4^i/i!, i=0..n)):
seq(a(n), n=0..25); # Alois P. Heinz, Jun 27 2017
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