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.

Showing 1-10 of 10 results.

A082545 a(n) = (2*n)! * Sum_{k=0..n} binomial(n,k)/(n+k)!.

Original entry on oeis.org

1, 3, 21, 229, 3393, 63591, 1442173, 38398641, 1174226049, 40558249963, 1561734494661, 66335687785533, 3081211226192641, 155369391396527439, 8452596370942940973, 493494408990278911561, 30777323181433121541633, 2042075395611656190239571
Offset: 0

Views

Author

Vladeta Jovovic, May 11 2003

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(n)*Evaluate(LaguerrePolynomial(n, n), -1): n in [0..40]]; // G. C. Greubel, Aug 11 2022
    
  • Maple
    a:= n-> simplify(n!*LaguerreL(n$2, -1)):
    seq(a(n), n=0..20);  # Alois P. Heinz, Jul 27 2017
  • Mathematica
    Table[n!*LaguerreL[n, n, -1], {n,0,17}] (* Jean-François Alcover, Jun 04 2019 *)
  • PARI
    a(n) = sum(k=0, n, k!*binomial(n, k)*binomial(2*n, k)); \\ Seiichi Manyama, May 01 2021
    
  • PARI
    a(n) = n!*pollaguerre(n, n, -1); \\ Seiichi Manyama, May 01 2021
    
  • SageMath
    [factorial(n)*gen_laguerre(n, n, -1) for n in (0..40)] # G. C. Greubel, Aug 11 2022

Formula

a(n) = n!*LaguerreL(n, n, -1).
n*a(n) + (n^3-5*n^2-n+2)*a(n-1) - 2*(n+1)*(2*n-3)*(n-1)^2*a(n-2) = 0. - Vladeta Jovovic, Jul 16 2004
E.g.f.: exp((-2*x+1-(1-4*x)^(1/2))/(2*x))/(1-4*x)^(1/2). - Mark van Hoeij, Oct 31 2011
a(n) ~ n^n*2^(2*n+1/2)/exp(n-1). - Vaclav Kotesovec, Sep 27 2012
a(n) = n!*binomial(2*n,n)*hypergeom([-n], [1+n], -1). - Peter Luschny, May 04 2017
a(n) = n! * [x^n] exp(x/(1 - x))/(1 - x)^(n+1). - Ilya Gutkovskiy, Nov 21 2017

A152059 a(n) is the number of ways 2n-1 seats can be occupied by at most n people for n>=1, with a(0)=1.

Original entry on oeis.org

1, 2, 13, 136, 1961, 36046, 805597, 21204548, 642451441, 22021483546, 842527453421, 35591363004352, 1645373927307673, 82625931422081126, 4478815087922020861, 260648364396903639676, 16208855884741850686817
Offset: 0

Views

Author

Paul D. Hanna, Nov 22 2008

Keywords

Comments

Let A(x) be the e.g.f. of this sequence, and B(x) be the e.g.f. of A082545, then B(x)/A(x) = C(x) where C(x) = 1 + x*C(x)^2 is the Catalan function (A000108). This follows from the fact that this sequence and A082545 form adjacent semi-diagonals of table A088699. - Paul D. Hanna, Aug 16 2022

Crossrefs

Programs

  • Magma
    [Factorial(n)*Evaluate(LaguerrePolynomial(n, n-1), -1): n in [0..40]]; // G. C. Greubel, Aug 11 2022
    
  • Mathematica
    Table[(-1)^n * HypergeometricU[-n, n, -1], {n, 0, 20}] (* Vaclav Kotesovec, Oct 02 2017 *)
  • PARI
    a(n)=sum(k=0,n,k!*binomial(2*n-1, k)*binomial(n, k))
    
  • PARI
    a(n) = n!*pollaguerre(n, n-1, -1); \\ Seiichi Manyama, May 01 2021
    
  • SageMath
    [factorial(n)*gen_laguerre(n, n-1, -1) for n in (0..40)] # G. C. Greubel, Aug 11 2022

Formula

a(n) = Sum_{k=0..n} k! * C(2*n-1,k) * C(n,k).
Central terms of triangle A086885 (after initial term).
a(n) = n! * [x^n] exp(x/(1 - x))/(1 - x)^n. - Ilya Gutkovskiy, Oct 02 2017
a(n) ~ 2^(2*n - 1/2) * n^n / exp(n-1). - Vaclav Kotesovec, Oct 02 2017
a(n) = n! * pollaguerre(n, n-1, -1). - Seiichi Manyama, May 01 2021
From Paul D. Hanna, Aug 16 2022: (Start)
E.g.f.: exp( (1-2*x - sqrt(1-4*x))/(2*x) ) / ((sqrt(1-4*x) - (1-4*x))/(2*x)), derived from the e.g.f for A082545 given by Mark van Hoeij.
E.g.f.: exp(C(x) - 1) / (2 - C(x)), where C(x) = (1 - sqrt(1-4*x))/(2*x) is the Catalan function (A000108). (End)

A176120 Triangle read by rows: Sum_{j=0..k} binomial(n, j)*binomial(k, j)*j!.

Original entry on oeis.org

1, 1, 2, 1, 3, 7, 1, 4, 13, 34, 1, 5, 21, 73, 209, 1, 6, 31, 136, 501, 1546, 1, 7, 43, 229, 1045, 4051, 13327, 1, 8, 57, 358, 1961, 9276, 37633, 130922, 1, 9, 73, 529, 3393, 19081, 93289, 394353, 1441729, 1, 10, 91, 748, 5509, 36046, 207775, 1047376, 4596553, 17572114
Offset: 0

Views

Author

Roger L. Bagula, Apr 09 2010

Keywords

Comments

The number of ways of placing any number k = 0, 1, ..., min(n,m) of non-attacking rooks on an n X m chessboard. - R. J. Mathar, Dec 19 2014
Let a be a partial permutation in S the symmetric inverse semigroup on [n] with rank(a) := |image(a)| = m. Then T(n,m) = |aS| where |aS| is the size of the principal right ideal generated by a. - Geoffrey Critzer, Dec 21 2021

Examples

			Triangle begins
  1;
  1,  2;
  1,  3,   7;
  1,  4,  13,   34;
  1,  5,  21,   73,  209;
  1,  6,  31,  136,  501,  1546;
  1,  7,  43,  229, 1045,  4051,  13327;
  1,  8,  57,  358, 1961,  9276,  37633,  130922;
  1,  9,  73,  529, 3393, 19081,  93289,  394353,  1441729;
  1, 10,  91,  748, 5509, 36046, 207775, 1047376,  4596553, 17572114;
  1, 11, 111, 1021, 8501, 63591, 424051, 2501801, 12975561, 58941091, 234662231;
		

References

  • O. Ganyushkin and V. Mazorchuk, Classical Finite Transformation Semigroups, Springer, 2009, page 46.

Crossrefs

Cf. A086885 (table without column 0), A129833 (row sums).

Programs

  • Magma
    A176120:=func< n,k| (&+[Factorial(j)*Binomial(n,j)*Binomial(k,j): j in [0..k]]) >;
    [A176120(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Aug 11 2022
    
  • Maple
    A176120 := proc(i,j)
            add(binomial(i,k)*binomial(j,k)*k!,k=0..j) ;
    end proc: # R. J. Mathar, Jul 28 2016
  • Mathematica
    T[n_, m_]:= T[n,m]= Sum[Binomial[n, k]*Binomial[m, k]*k!, {k, 0, m}];
    Table[T[n, m], {n,0,12}, {m,0,n}]//Flatten
  • SageMath
    def A176120(n,k): return sum(factorial(j)*binomial(n,j)*binomial(k,j) for j in (0..k))
    flatten([[A176120(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Aug 11 2022

Formula

Sum_{k=0..n} T(n, k) = A129833(n).
T(n,m) = A088699(n, m). - Peter Bala, Aug 26 2013
T(n,m) = A086885(n, m). - R. J. Mathar, Dec 19 2014
From G. C. Greubel, Aug 11 2022: (Start)
T(n, k) = Hypergeometric2F1([-n, -k], [], 1).
T(2*n, n) = A082545(n).
T(2*n+1, n) = A343832(n).
T(n, n) = A002720(n).
T(n, n-1) = A000262(n), n >= 1.
T(n, 1) = A000027(n+1).
T(n, 2) = A002061(n+1).
T(n, 3) = A135859(n+1). (End)

A343830 a(n) = numerator of (1/e) * Sum_{a_1>=1, a_2>=1, ... , a_n>=1} a_1 * a_2 * ... * a_n / (a_1 + a_2 + ... + a_n)!.

Original entry on oeis.org

1, 2, 31, 179, 787, 6631, 2456299, 33235913, 158433901, 17980176031, 2794938616471, 8546650588601, 5595650767265101, 35480190026972501, 15523069639558351459, 455264603021602214213, 57023540590242398853649, 949437664962426221725789, 5469912218467062529961407
Offset: 1

Views

Author

Seiichi Manyama, Apr 30 2021

Keywords

Examples

			1, 2/3, 31/120, 179/2520, 787/51840, 6631/2494800, 2456299/6227020800, ...
		

References

  • O. Furdui, Limits, Series and Fractional Part Integrals. Problems in Mathematical Analysis, Springer, New York, 2013. See Problem 3.114 and 3.118.

Crossrefs

Cf. A343831 (denominator), A343832.

Programs

  • Mathematica
    a[n_] := Numerator @ Sum[Binomial[n - 1, k]/(k + n)!, {k, 0, n - 1}]; Array[a, 20] (* Amiram Eldar, May 01 2021 *)
  • PARI
    a(n) = numerator(sum(j=0, n, (-1)^(n+j-1)*binomial(n, j)*sum(k=0, n+j-1, (-1)^k/k!)));
    
  • PARI
    a(n) = numerator(sum(k=0, n-1, binomial(n-1, k)/(k+n)!));

Formula

b(n) = (1/e) * Sum_{a_1>=1, a_2>=1, ... , a_n>=1} a_1 * a_2 * ... * a_n / (a_1 + a_2 + ... + a_n)! = Sum_{j=0..n} (-1)^(n+j-1) * binomial(n,j) * Sum_{k=0..n+j-1} (-1)^k/k! = Sum_{k=0..n-1} binomial(n-1,k)/(k+n)!.
a(n) = numerator of b(n).

A343831 a(n) = denominator of (1/e) * Sum_{a_1>=1, a_2>=1, ... , a_n>=1} a_1 * a_2 * ... * a_n / (a_1 + a_2 + ... + a_n)!.

Original entry on oeis.org

1, 3, 120, 2520, 51840, 2494800, 6227020800, 653837184000, 27360571392000, 30411275102208000, 51090942171709440000, 1846572624206069760000, 15511210043330985984000000, 1361108681302294020096000000, 8841761993739701954543616000000
Offset: 1

Views

Author

Seiichi Manyama, Apr 30 2021

Keywords

Examples

			1, 2/3, 31/120, 179/2520, 787/51840, 6631/2494800, 2456299/6227020800, ...
		

References

  • O. Furdui, Limits, Series and Fractional Part Integrals. Problems in Mathematical Analysis, Springer, New York, 2013. See Problem 3.114 and 3.118.

Crossrefs

Cf. A343830 (numerator), A343832.

Programs

  • Mathematica
    a[n_] := Denominator @ Sum[Binomial[n - 1, k]/(k + n)!, {k, 0, n - 1}]; Array[a, 20] (* Amiram Eldar, May 01 2021 *)
  • PARI
    a(n) = denominator(sum(j=0, n, (-1)^(n+j-1)*binomial(n, j)*sum(k=0, n+j-1, (-1)^k/k!)));
    
  • PARI
    a(n) = denominator(sum(k=0, n-1, binomial(n-1, k)/(k+n)!));

Formula

b(n) = (1/e) * Sum_{a_1>=1, a_2>=1, ... , a_n>=1} a_1 * a_2 * ... * a_n / (a_1 + a_2 + ... + a_n)! = Sum_{j=0..n} (-1)^(n+j-1) * binomial(n,j) * Sum_{k=0..n+j-1} (-1)^k/k! = Sum_{k=0..n-1} binomial(n-1,k)/(k+n)!.
a(n) = denominator of b(n).

A343896 a(n) = Sum_{k=0..n} (-1)^(n-k) * k! * binomial(n,k) * binomial(2*n+1,k).

Original entry on oeis.org

1, 2, 11, 104, 1405, 24694, 534223, 13719404, 407730041, 13760958410, 519827337331, 21726980525392, 995403499490101, 49600090942276094, 2670566242480261175, 154500457959360271124, 9557826199486960327153, 629586464929967678553874, 43994787057844036765113691
Offset: 0

Views

Author

Seiichi Manyama, May 03 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := n!*LaguerreL[n, n + 1, 1]; Array[a, 19, 0] (* Amiram Eldar, May 11 2021 *)
  • PARI
    a(n) = sum(k=0, n, (-1)^(n-k)*k!*binomial(n, k)*binomial(2*n+1, k));
    
  • PARI
    a(n) = (2*n+1)!*sum(k=0, n, (-1)^k*binomial(n, k)/(k+n+1)!);
    
  • PARI
    a(n) = n!*sum(k=0, n, (-1)^(n-k)*binomial(2*n+1, k)/(n-k)!);
    
  • PARI
    a(n) = n!*pollaguerre(n, n+1, 1);

Formula

a(n) = (2*n+1)! * Sum_{k=0..n} (-1)^k * binomial(n,k)/(k+n+1)!.
a(n) = n! * Sum_{k=0..n} (-1)^(n-k) * binomial(2*n+1,k)/(n-k)!.
a(n) = n! * LaguerreL(n, n+1, 1).
a(n) = n! * [x^n] exp(-x/(1 - x))/(1 - x)^(n+2).
a(n) ~ 2^(2*n + 3/2) * n^n / exp(n+1). - Vaclav Kotesovec, May 03 2021

A380491 a(n) = n! * Sum_{k=0..n} binomial(2*n-3,k)/(n-k)!.

Original entry on oeis.org

1, 0, 3, 34, 501, 9276, 207775, 5470158, 165625929, 5671386136, 216730118331, 9144481575450, 422249317829053, 21180324426577044, 1146880568461500951, 66677192513929212166, 4142571510546929867025, 273910161452560881843888, 19204878684852222745880179
Offset: 0

Views

Author

Seiichi Manyama, Jan 25 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*pollaguerre(n, n-3, -1);

Formula

a(n) = n! * LaguerreL(n, n-3, -1).
a(n) = n! * [x^n] exp(x/(1 - x))/(1 - x)^(n-2).

A380492 a(n) = n! * Sum_{k=0..n} binomial(2*n-2,k)/(n-k)!.

Original entry on oeis.org

1, 1, 7, 73, 1045, 19081, 424051, 11109337, 335262313, 11453449105, 436944953791, 18412283563081, 849345673881277, 42570185481576793, 2303643608370636715, 133859418832759525081, 8312945340897388101841, 549460711493172343519777, 38513032385247860120975863
Offset: 0

Views

Author

Seiichi Manyama, Jan 25 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*pollaguerre(n, n-2, -1);

Formula

a(n) = n! * LaguerreL(n, n-2, -1).
a(n) = n! * [x^n] exp(x/(1 - x))/(1 - x)^(n-1).

A380493 a(n) = n! * Sum_{k=0..n} binomial(2*n+3,k)/(n-k)!.

Original entry on oeis.org

1, 6, 57, 748, 12585, 259026, 6315001, 178134552, 5711078673, 205209960670, 8171229107481, 357235056697476, 17014791129640057, 877089297426429738, 48657292133825026905, 2890717184573264397616, 183125115830192864360481, 12323226433255671469949622
Offset: 0

Views

Author

Seiichi Manyama, Jan 25 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*pollaguerre(n, n+3, -1);

Formula

a(n) = n! * LaguerreL(n, n+3, -1).
a(n) = n! * [x^n] exp(x/(1 - x))/(1 - x)^(n+4).

A343890 Coefficient triangle of generalized Laguerre polynomials n!*L(n,n+1,x) (rising powers of x).

Original entry on oeis.org

1, 3, -1, 20, -10, 1, 210, -126, 21, -1, 3024, -2016, 432, -36, 1, 55440, -39600, 9900, -1100, 55, -1, 1235520, -926640, 257400, -34320, 2340, -78, 1, 32432400, -25225200, 7567560, -1146600, 95550, -4410, 105, -1, 980179200, -784143360, 249500160, -41583360, 3998400, -228480, 7616, -136, 1
Offset: 0

Views

Author

Seiichi Manyama, May 03 2021

Keywords

Examples

			The triangle begins:
        1;
        3,      -1;
       20,     -10,      1;
      210,    -126,     21,     -1;
     3024,   -2016,    432,    -36,    1;
    55440,  -39600,   9900,  -1100,   55,  -1;
  1235520, -926640, 257400, -34320, 2340, -78, 1;
		

Crossrefs

Row sums (signed) give A343896, row sums (unsigned) give A343832.
Cf. A343861.

Programs

  • Mathematica
    T[n_, k_] := (-1)^k * (2*n + 1)! * Binomial[n, k]/(k + n + 1)!; Table[T[n, k], {n, 0, 8}, {k, 0, n}] // Flatten (* Amiram Eldar, May 03 2021 *)
  • PARI
    T(n, k) = (-1)^k*(2*n+1)!*binomial(n,k)/(k+n+1)!;
    
  • PARI
    row(n) = Vecrev(n!*pollaguerre(n, n+1));

Formula

T(n, k) = (-1)^k * n! * binomial(2*n+1,n-k)/k! = (-1)^k * (2*n+1)! * binomial(n,k)/(k+n+1)!.
Showing 1-10 of 10 results.