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 11-20 of 20 results.

A277422 a(n) = n!*LaguerreL(n, -8*n).

Original entry on oeis.org

1, 9, 322, 19446, 1649688, 180184120, 24070390992, 3801662863152, 692979602529664, 143184960501077376, 33069665092749868800, 8442378658666161822976, 2360674573114695421197312, 717531421372546588398529536, 235551703250624390582942574592
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 14 2016

Keywords

Comments

In general, if m > 0 and a(n) = n!*LaguerreL(n, -m*n), then a(n) ~ sqrt(1/2 + (m+2)/(2*sqrt(m*(m+4)))) * (2+m+sqrt(m*(m+4)))^n * exp(n*(sqrt(m*(m+4))-m-2)/2) * n^n / 2^n.
For m > 4, (-1)^n * n! * LaguerreL(n, m*n) ~ sqrt(1/2 + (m-2)/(2*sqrt(m*(m-4)))) * exp((m - 2 - sqrt(m*(m-4)))*n/2) * ((m - 2 + sqrt(m*(m-4)))/2)^n * n^n. - Vaclav Kotesovec, Feb 20 2020

Crossrefs

Cf. A277373 (m=1), A277391 (m=2), A277392 (m=3), A277418 (m=4), A277419 (m=5), A277420 (m=6), A277421 (m=7).

Programs

  • Magma
    [Factorial(n)*(&+[Binomial(n,k)*(8)^k*n^k/Factorial(k): k in [0..n]]): n in [0..20]]; // G. C. Greubel, May 16 2018
  • Mathematica
    Table[n!*LaguerreL[n, -8*n], {n, 0, 20}]
    Flatten[{1, Table[n!*Sum[Binomial[n, k] * 8^k * n^k / k!, {k, 0, n}], {n, 1, 20}]}]
  • PARI
    for(n=0, 30, print1(n!*sum(k=0,n, binomial(n,k)*(8)^k*n^k/k!), ", ")) \\ G. C. Greubel, May 16 2018
    

Formula

a(n) = n! * Sum_{k=0..n} binomial(n, k) * 8^k * n^k / k!.
a(n) ~ sqrt(2 + 5/sqrt(6)) * (5 + 2*sqrt(6))^n * exp((-5 + 2*sqrt(6))*n) * n^n / 2.

A295382 Expansion of e.g.f. exp(-2*x/(1 - x))/(1 - x).

Original entry on oeis.org

1, -1, -2, -2, 8, 88, 592, 3344, 14464, 2944, -1121536, -21603584, -317969408, -4202380288, -51322677248, -562045749248, -4751724347392, -3419742961664, 1260396818661376, 45221885372727296, 1218206507254153216, 29421299633821057024, 669044215287581769728, 14528992234596624498688
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 21 2017

Keywords

Crossrefs

Column k=2 of A295381.

Programs

  • Magma
    [Factorial(n)*(&+[(-1)^k*Binomial(n,k)*2^k/Factorial(k): k in [0..n]]): n in [0..30]]; // G. C. Greubel, Feb 06 2018
  • Maple
    a:=series(exp(-2*x/(1-x))/(1-x),x=0,24): seq(n!*coeff(a,x,n),n=0..23); # Paolo P. Lava, Mar 27 2019
  • Mathematica
    nmax = 23; CoefficientList[Series[Exp[-2 x/(1 - x)]/(1 - x), {x, 0, nmax}], x] Range[0, nmax]!
    Table[n! LaguerreL[n, 2], {n, 0, 23}]
    Table[n! Hypergeometric1F1[-n, 1, 2], {n, 0, 23}]
    Table[n! Sum[(-1)^k Binomial[n, k] 2^k/k!, {k, 0, n}], {n, 0, 23}]
  • PARI
    my(x='x+O('x^30)); Vec(serlaplace(exp(-2*x/(1-x))/(1-x))) \\ G. C. Greubel, Feb 06 2018
    

Formula

E.g.f.: exp(-2*x/(1 - x))/(1 - x).
a(n) = n!*Laguerre(n,2).
a(n) = n!*Sum_{k=0..n} (-1)^k*binomial(n,k)*2^k/k!.
a(n) = n!*A160623(n)/A160624(n).
a(n) = Sum_{k=0..n} (-2)^(n-k)*k!*binomial(n,k)^2. - Ridouane Oudra, Jul 08 2025

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

A274246 a(n) = Sum_{k=0..n} binomial(n, k)^3 * 2^(n-k) * k!.

Original entry on oeis.org

1, 3, 22, 230, 3048, 48152, 875536, 17907024, 405320320, 10030449536, 268836428544, 7744939895552, 238352004594688, 7795463142466560, 269761049981827072, 9839883848966985728, 377091995258812268544, 15139047281589466136576, 635088889901946682408960, 27775758544209632635060224, 1263876454164193257295446016
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 12 2016

Keywords

Crossrefs

Programs

  • Magma
    [(&+[Binomial(n,j)^3*Factorial(j)*2^(n-j): j in [0..n]]): n in [0..30]]; // G. C. Greubel, Dec 27 2022
    
  • Maple
    f:= gfun:-rectoproc({n*(2*n - 5)*a(n) = (6*n^3 - 13*n^2 - 8*n + 6)*a(n-1) - (n-1)*(6*n^3 - 51*n^2 + 124*n - 90)*a(n-2) + (n-2)^3*(n-1)*(2*n - 3)*a(n-3),a(0)=1,a(1)=3,a(2)=22},a(n),remember):
    map(f, [$0..30]); # Robert Israel, Nov 16 2017
  • Mathematica
    Table[Sum[Binomial[n, k]^3 * 2^(n-k) * k!, {k, 0, n}], {n, 0, 20}]
  • SageMath
    def A274246(n): return sum(binomial(n,j)^3*factorial(j)*2^(n-j) for j in range(n+1))
    [A274246(n) for n in range(31)] # G. C. Greubel, Dec 27 2022

Formula

Recurrence: n*(2*n - 5)*a(n) = (6*n^3 - 13*n^2 - 8*n + 6)*a(n-1) - (n-1)*(6*n^3 - 51*n^2 + 124*n - 90)*a(n-2) + (n-2)^3*(n-1)*(2*n - 3)*a(n-3).
a(n) ~ n^(n - 1/6) * exp(3*2^(1/3)*n^(2/3) - 2^(2/3)*n^(1/3) - n + 2/3) / (2^(5/6)*sqrt(3*Pi)) * (1 + 31*2^(1/3)/(27*n^(1/3)) + 3437/(3645*2^(1/3) * n^(2/3))).
Sum_{n>=0} a(n) * x^n / n!^3 = BesselI(0,2*sqrt(x)) * Sum_{n>=0} 2^n * x^n / n!^3. - Ilya Gutkovskiy, Jun 19 2022
a(n) = 2^n * Hypergeometric3F1([-n, -n, -n], [1], -1/2). - G. C. Greubel, Dec 27 2022

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

A160615 Numerator of Laguerre(n, -2).

Original entry on oeis.org

1, 3, 7, 43, 27, 719, 3661, 13991, 66769, 133261, 2363513, 116441047, 513267739, 153434147, 96790969339, 2053217625931, 136839921293, 67725860135459, 837687671342383, 7232743280136193, 2996031500521181, 4142815387557270467
Offset: 0

Views

Author

N. J. A. Sloane, Nov 14 2009

Keywords

Examples

			1, 3, 7, 43/3, 27, 719/15, 3661/45, 13991/105, 66769/315, 133261/405, 2363513/4725, 116441047/155925, ...
		

Crossrefs

For denominators see A160616.
Cf. A087912.

Programs

  • Magma
    [Numerator((&+[Binomial(n,k)*(2^k/Factorial(k)): k in [0..n]])): n in [0..30]]; // G. C. Greubel, May 06 2018
  • Mathematica
    Numerator[Table[LaguerreL[n, -2], {n, 0, 50}]] (* G. C. Greubel, May 06 2018 *)
  • PARI
    for(n=0,30, print1(numerator(sum(k=0,n, binomial(n,k)*(2^k/k!))), ", ")) \\ G. C. Greubel, May 06 2018
    

Formula

Numerators of coefficients in expansion of exp(2*x/(1 - x))/(1 - x). - Ilya Gutkovskiy, Aug 29 2018

A160616 Denominator of Laguerre(n, -2).

Original entry on oeis.org

1, 1, 1, 3, 1, 15, 45, 105, 315, 405, 4725, 155925, 467775, 96525, 42567525, 638512875, 30405375, 10854718875, 97692469875, 618718975875, 189403768125, 194896477400625, 238206805711875, 7044115540336875, 8701554491004375
Offset: 0

Views

Author

N. J. A. Sloane, Nov 14 2009

Keywords

Examples

			1, 3, 7, 43/3, 27, 719/15, 3661/45, 13991/105, 66769/315, 133261/405, 2363513/4725, 116441047/155925, ...
		

Crossrefs

For numerators see A160615.
Cf. A087912.

Programs

  • Magma
    [Denominator((&+[Binomial(n,k)*(2^k/Factorial(k)): k in [0..n]])): n in [0..30]]; // G. C. Greubel, May 06 2018
  • Mathematica
    Denominator[Table[LaguerreL[n, -2], {n, 0, 50}]] (* G. C. Greubel, May 06 2018 *)
  • PARI
    a(n) = sum(k=0, n, (-1)^k*binomial(n, k)*(-2)^k/k!); \\ Michel Marcus, Aug 10 2015
    

Formula

Denominators of coefficients in expansion of exp(2*x/(1 - x))/(1 - x). - Ilya Gutkovskiy, Aug 29 2018

A331333 Interpolating the factorial and the powers of 2. Triangle read by rows, T(n, k) for 0 <= k <= n.

Original entry on oeis.org

1, 1, 2, 2, 8, 4, 6, 36, 36, 8, 24, 192, 288, 128, 16, 120, 1200, 2400, 1600, 400, 32, 720, 8640, 21600, 19200, 7200, 1152, 64, 5040, 70560, 211680, 235200, 117600, 28224, 3136, 128, 40320, 645120, 2257920, 3010560, 1881600, 602112, 100352, 8192, 256
Offset: 0

Views

Author

Peter Luschny, Jan 19 2020

Keywords

Examples

			Triangle starts:
  [0] 1
  [1] 1,     2
  [2] 2,     8,      4
  [3] 6,     36,     36,      8
  [4] 24,    192,    288,     128,     16
  [5] 120,   1200,   2400,    1600,    400,     32
  [6] 720,   8640,   21600,   19200,   7200,    1152,   64
  [7] 5040,  70560,  211680,  235200,  117600,  28224,  3136,   128
  [8] 40320, 645120, 2257920, 3010560, 1881600, 602112, 100352, 8192, 256
		

Crossrefs

T(n, 0) = A000142(n), T(n, n) = A000079(n).
Row sums: A087912, alternating row sums: A295382, antidiagonal sums: A222467, positive half sums: A129683, negative half sums: A331334.
Cf. A021009.

Programs

  • Maple
    A331333 := proc(n, k) local S; S := proc(n, k) option remember;
    `if`(k = 0, 1, `if`(k > n, 0, 2*S(n-1, k-1)/k + S(n-1, k))) end: n!*S(n, k) end:
    seq(seq(A331333(n, k), k=0..n), n=0..8);

Formula

T(n, k) = n!*S(n, k) where S(n, k) is recursively defined by:
if k = 0 then 1 else if k > n then 0 else 2*S(n-1, k-1)/k + S(n-1, k).
From Peter Bala, Jan 19 2020: (Start)
T(n,k) = 2^k*(n!/k!)*binomial(n,k).
E.g.f.: exp((2*x*t)/(1 - x))/(1 - x) = 1 + (1 + 2*t)*x + (2 + 8*t + 4*t^2)*x^2/2! + .... Cf. A021009. (End)

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.

A375854 Triangle read by rows: T(n, k) = 2^k * hypergeom([-n, -k], [], 1/2).

Original entry on oeis.org

1, 1, 3, 1, 4, 14, 1, 5, 22, 86, 1, 6, 32, 152, 648, 1, 7, 44, 248, 1256, 5752, 1, 8, 58, 380, 2248, 12032, 58576, 1, 9, 74, 554, 3768, 23272, 130768, 671568, 1, 10, 92, 776, 5984, 42112, 270400, 1586944, 8546432, 1, 11, 112, 1052, 9088, 72032, 523072, 3479744, 21241984, 119401856
Offset: 0

Views

Author

Detlef Meya, Aug 31 2024

Keywords

Examples

			Triangle starts:
[0] 1;
[1] 1, 3;
[2] 1, 4, 14;
[3] 1, 5, 22, 86;
[4] 1, 6, 32, 152, 648;
[5] 1, 7, 44, 248, 1256, 5752;
[6] 1, 8, 58, 380, 2248, 12032, 58576;
[7] 1, 9, 74, 554, 3768, 23272, 130768, 671568;
[8] 1, 10, 92, 776, 5984, 42112, 270400, 1586944, 8546432;
[9] 1, 11, 112, 1052, 9088, 72032, 523072, 3479744, 21241984, 119401856;
...
		

Crossrefs

Cf. A375855, A000012, A087912 (main diagonal).

Programs

  • Maple
    T := (n, k) -> 2^k * hypergeom([-n, -k], [], 1/2):
    for n from 0 to 9 do seq(simplify(T(n, k)), k=0..n) od; # Peter Luschny, Sep 02 2024
  • Mathematica
    T[n_, k_] := Sum[2^(k - j)*Binomial[n, j]*Binomial[k, j]*j!, {j, 0, k}];
    Table[T[n, k], {n, 0, 9}, {k, 0, n}] // Flatten
  • Python
    from math import isqrt, comb, factorial
    def A375854(n):
        a = (m:=isqrt(k:=n+1<<1))-(k<=m*(m+1))
        b = n-comb(a+1,2)
        return sum(comb(a,j)*comb(b,j)*factorial(j)<Chai Wah Wu, Nov 13 2024

Formula

T(n, k) = Sum_{j=0..k} 2^(k - j)*binomial(n, j)*binomial(k, j)*j!.
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