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.

Previous Showing 11-17 of 17 results.

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

A277372 a(n) = Sum_{k=1..n} binomial(n,n-k)*n^(n-k)*n!/(n-k)!.

Original entry on oeis.org

0, 1, 10, 141, 2584, 58745, 1602576, 51165205, 1874935168, 77644293201, 3588075308800, 183111507687581, 10230243235200000, 621111794820235849, 40722033570202507264, 2867494972696071121125, 215840579093024990396416, 17294837586403146090259745, 1469799445329208661211021312
Offset: 0

Views

Author

Peter Luschny, Oct 11 2016

Keywords

Crossrefs

Programs

  • Maple
    a := n -> add(binomial(n,n-k)*n^(n-k)*n!/(n-k)!, k=1..n):
    seq(a(n), n=0..18);
    # Alternatively:
    A277372 := n -> n!*LaguerreL(n,-n) - n^n:
    seq(simplify(A277372(n)), n=0..18);
  • PARI
    a(n) = sum(k=1, n, binomial(n,n-k)*n^(n-k)*n!/(n-k)!); \\ Michel Marcus, Oct 12 2016

Formula

a(n) = n!*LaguerreL(n, -n) - n^n.
a(n) = (-1)^n*KummerU(-n, 1, -n) - n^n.
a(n) = n^n*(hypergeom([-n, -n], [], 1/n) - 1) for n>=1.
a(n) ~ n^n * phi^(2*n+1) * exp(n/phi-n) / 5^(1/4), where phi = A001622 = (1+sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Oct 12 2016

A160613 Numerator of Laguerre(n, -3).

Original entry on oeis.org

1, 4, 23, 28, 491, 1249, 19223, 15476, 3515161, 1512661, 14496817, 228800107, 11770539419, 60428965661, 5262254717509, 2521163372543, 976843770850217, 887131806309703, 73511154681979031, 255777165814872577
Offset: 0

Views

Author

N. J. A. Sloane, Nov 14 2009

Keywords

Crossrefs

For denominators see A160614.
Cf. A277382.

Programs

  • Magma
    [Numerator((&+[Binomial(n,k)*(3^k/Factorial(k)): k in [0..n]])): n in [0..30]]; // G. C. Greubel, May 09 2018
  • Mathematica
    Numerator[Table[LaguerreL[n, -3], {n, 0, 50}]] (* G. C. Greubel, May 09 2018 *)
  • PARI
    for(n=0,30, print1(numerator(sum(k=0,n, binomial(n,k)*(3^k/k!))), ", ")) \\ G. C. Greubel, May 09 2018
    

A160614 Denominator of Laguerre(n, -3).

Original entry on oeis.org

1, 1, 2, 1, 8, 10, 80, 35, 4480, 1120, 6400, 61600, 1971200, 6406400, 358758400, 112112000, 28700672000, 17425408000, 975822848000, 2317579264000, 370812682240000, 49917091840000, 57105153064960000, 41044328765440000
Offset: 0

Views

Author

N. J. A. Sloane, Nov 14 2009

Keywords

Crossrefs

For numerators see A160613.
Cf. A277382.

Programs

  • Magma
    [Denominator((&+[Binomial(n,k)*(3^k/Factorial(k)): k in [0..n]])): n in [0..30]]; // G. C. Greubel, May 06 2018
  • Mathematica
    Denominator[Table[LaguerreL[n, -3], {n, 0, 50}]] (* G. C. Greubel, May 06 2018 *)
  • PARI
    for(n=0,30, print1(denominator(sum(k=0,n, binomial(n,k)*(3^k/k!))), ", ")) \\ G. C. Greubel, May 06 2018
    

A277386 a(n) = Sum_{k=0..n} binomial(n, k)^3 * 3^(n-k) * k!.

Original entry on oeis.org

1, 4, 35, 438, 6873, 127488, 2703447, 64121130, 1674999009, 47638235484, 1461975938379, 48068355965886, 1683311251028265, 62477888170824792, 2447583053876363727, 100842325515959413842, 4356021203508275392833, 196739133595421931988020, 9268144156277932321747251
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 12 2016

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[Binomial[n, k]^3 * 3^(n-k) * k!, {k, 0, n}], {n, 0, 20}]

Formula

Recurrence: n*(8*n - 23)*a(n) = 3*(8*n^3 - 15*n^2 - 30*n + 17)*a(n-1) - (n-1)*(24*n^3 - 261*n^2 + 770*n - 666)*a(n-2) + (n-2)^3*(n-1)*(8*n - 15)*a(n-3).
a(n) ~ n^(n - 1/6) * exp(3*3^(1/3)*n^(2/3) - 3^(2/3)*n^(1/3) - n +1) / (3^(5/6)*sqrt(2*Pi)) * (1 + 19/(6*3^(2/3)*n^(1/3)) + 1193/(1080*3^(1/3) * n^(2/3))).
Sum_{n>=0} a(n) * x^n / n!^3 = BesselI(0,2*sqrt(x)) * Sum_{n>=0} 3^n * x^n / n!^3. - Ilya Gutkovskiy, Jun 19 2022

A343847 T(n, k) = (n - k)! * [x^(n-k)] exp(k*x/(1 - x))/(1 - x). Triangle read by rows, T(n, k) for 0 <= k <= n.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 6, 7, 3, 1, 24, 34, 14, 4, 1, 120, 209, 86, 23, 5, 1, 720, 1546, 648, 168, 34, 6, 1, 5040, 13327, 5752, 1473, 286, 47, 7, 1, 40320, 130922, 58576, 14988, 2840, 446, 62, 8, 1, 362880, 1441729, 671568, 173007, 32344, 4929, 654, 79, 9, 1
Offset: 0

Views

Author

Peter Luschny, May 07 2021

Keywords

Examples

			Triangle starts:
0:     1;
1:     1,      1;
2:     2,      2,     1;
3:     6,      7,     3,     1;
4:    24,     34,    14,     4,    1;
5:   120,    209,    86,    23,    5,   1;
6:   720,   1546,   648,   168,   34,   6,  1;
7:  5040,  13327,  5752,  1473,  286,  47,  7,  1;
8: 40320, 130922, 58576, 14988, 2840, 446, 62,  8,  1;
.
Array whose upward read antidiagonals are the rows of the triangle.
n\k   0       1       2        3        4         5        6
-----------------------------------------------------------------
0:    1,      1,      1,       1,       1,        1,        1, ...
1:    1,      2,      3,       4,       5,        6,        7, ...
2:    2,      7,     14,      23,      34,       47,       62, ...
3:    6,     34,     86,     168,     286,      446,      654, ...
4:   24,    209,    648,    1473,    2840,     4929,     7944, ...
5:  120,   1546,   5752,   14988,   32344,    61870,   108696, ...
6:  720,  13327,  58576,  173007,  414160,   866695,  1649232, ...
7: 5040, 130922, 671568, 2228544, 5876336, 13373190, 27422352, ...
		

Crossrefs

Row sums: A343848. T(2*n, n) = A277373(n). Variant: A289192.
Cf. A021009 (Laguerre polynomials), A344048.

Programs

  • Maple
    T := proc(n, k) option remember;
    if n = k then return 1 elif n = k+1 then return k+1 fi;
    (2*n-k-1)*T(n-1, k) - (n-k-1)^2*T(n-2, k) end:
    seq(print(seq(T(n ,k), k = 0..n)), n = 0..7);
  • Mathematica
    T[n_, k_] := (-1)^(n - k) HypergeometricU[k - n, 1, -k];
    Table[T[n, k], {n, 0, 9}, {k, 0, n}] // Flatten
    (* Alternative: *)
    TL[n_, k_] := (n - k)! LaguerreL[n - k, -k];
    Table[TL[n, k], {n, 0, 9}, {k, 0, n}] // Flatten
  • PARI
    T(n, k) = (n - k)!*sum(j=0, n - k, binomial(n - k, j) * k^j / j!)
    for(n=0, 9, for(k=0, n, print(T(n, k))))
    
  • SageMath
    # Columns of the array.
    def column(k, len):
        R. = PowerSeriesRing(QQ, default_prec=len)
        f = exp(k * x / (1 - x)) / (1 - x)
        return f.egf_to_ogf().list()
    for col in (0..6): print(column(col, 20))

Formula

T(n, k) = (-1)^(n - k)*U(k - n, 1, -k), where U is the Kummer U function.
T(n, k) = (n - k)! * L(n - k, -k), where L is the Laguerre polynomial function.
T(n, k) = (n - k)! * Sum_{j = 0..n - k} binomial(n - k, j) k^j / j!.
T(n, k) = (2*n-k-1)*T(n-1, k) - (n-k-1)^2*T(n-2, k) for n - k >= 2.

A299018 Triangle read by rows: T(n,k) is the coefficient of x^k in the polynomial P(n) = n*(x + 1)*P(n - 1) - (n - 2)^2*x*P(n - 2).

Original entry on oeis.org

1, 2, 2, 6, 11, 6, 24, 60, 60, 24, 120, 366, 501, 366, 120, 720, 2532, 4242, 4242, 2532, 720, 5040, 19764, 38268, 46863, 38268, 19764, 5040, 40320, 172512, 373104, 528336, 528336, 373104, 172512, 40320, 362880, 1668528, 3942108, 6237828, 7213761, 6237828, 3942108, 1668528, 362880
Offset: 1

Views

Author

F. Chapoton, Jan 31 2018

Keywords

Examples

			For n = 3, the polynomial is 6*x^2 + 11*x + 6.
The first few polynomials, as a table:
[1],
[2,    2],
[6,    11,    6],
[24,   60,    60,  24],
[120,  366,   501, 366, 120]
		

Crossrefs

Very similar to A298854.
Row sums are A277382(n-1) for n>0.
Leftmost and rightmost columns are A000142.
Alternating row sums are A177145.
Alternating row sum of row 2*n+1 is A001818(n).

Programs

  • Maple
    P:= proc(n) option remember; expand(`if`(n<2, n,
          n*(x+1)*P(n-1)-(n-2)^2*x*P(n-2)))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..n-1))(P(n)):
    seq(T(n), n=1..12);  # Alois P. Heinz, Jan 31 2018
    A := proc(n,k) ## n >= 0 and k = 0 .. n
        option remember;
        if n = 0 and k = 0 then
            1
        elif n > 0 and k >= 0 and k <= n then
            (n+1)*(A(n-1,k)+A(n-1,k-1))-(n-1)^2*A(n-2,k-1)
        else
            0
        end if;
    end proc: # Yu-Sheng Chang, Apr 14 2020
  • Mathematica
    P[n_] := P[n] = Expand[If[n < 2, n, n (x+1) P[n-1] - (n-2)^2 x P[n-2]]];
    row[n_] := CoefficientList[P[n], x];
    row /@ Range[12] // Flatten (* Jean-François Alcover, Dec 10 2019 *)
  • Sage
    @cached_function
    def poly(n):
        x = polygen(ZZ, 'x')
        if n < 1:
            return x.parent().zero()
        elif n == 1:
            return x.parent().one()
        else:
            return n * (x + 1) * poly(n - 1) - (n - 2)**2 * x * poly(n - 2)

Formula

P(0) = 0, P(1) = 1 and P(n) = n * (x + 1) * P(n - 1) - (n - 2)^2 * x * P(n - 2).
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