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.

A343832 a(n) = Sum_{k=0..n} k! * binomial(n,k) * binomial(2*n+1,k).

Original entry on oeis.org

1, 4, 31, 358, 5509, 106096, 2456299, 66471826, 2059640713, 71920704124, 2794938616471, 119653108240414, 5595650767265101, 283841520215780008, 15523069639558351459, 910529206043204428426, 57023540590242398853649, 3797750659849704886903156, 268025698704886063968108943
Offset: 0

Views

Author

Seiichi Manyama, May 01 2021

Keywords

Comments

Let A(x) be the e.g.f. of this sequence, and B(x) be the e.g.f. of A082545, then A(x)/B(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
    
  • Maple
    a := n -> add(k!*binomial(n, k)*binomial(2*n+1, k), k=0..n):
    a := n -> n!*add(binomial(2*n+1, k)/(n-k)!, k=0..n):
    a := n -> (-1)^n*KummerU(-n, n+2, -1):
    a := n -> n!*LaguerreL(n, n+1, -1): # Peter Luschny, May 02 2021
  • Mathematica
    a[n_] := Sum[k! * Binomial[n, k] * Binomial[2*n+1, k], {k, 0, n}]; Array[a, 20, 0] (* Amiram Eldar, May 01 2021 *)
    Table[(-1)^n * HypergeometricU[-n, 2 + n, -1], {n, 0, 20}] (* Vaclav Kotesovec, May 02 2021 *)
  • PARI
    a(n) = sum(k=0, n, k!*binomial(n, k)*binomial(2*n+1, k));
    
  • PARI
    a(n) = (2*n+1)!*sum(k=0, n, binomial(n, k)/(k+n+1)!);
    
  • PARI
    a(n) = n!*sum(k=0, n, binomial(2*n+1, k)/(n-k)!);
    
  • PARI
    a(n) = n!*pollaguerre(n, n+1, -1);
    
  • SageMath
    [factorial(n)*gen_laguerre(n, n+1, -1) for n in (0..40)] # G. C. Greubel, Aug 11 2022

Formula

a(n) = (2*n+1)! * Sum_{k=0..n} binomial(n,k)/(k+n+1)!.
a(n) = n! * Sum_{k=0..n} 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) == 1 (mod 3).
a(n) ~ 2^(2*n + 3/2) * n^n / exp(n-1). - Vaclav Kotesovec, May 02 2021
From Paul D. Hanna, Aug 16 2022: (Start)
E.g.f.: exp( (1-2*x - sqrt(1-4*x))/(2*x) ) * (1 - sqrt(1-4*x)) / (2*x*sqrt(1-4*x)), derived from the e.g.f for A082545 given by Mark van Hoeij.
E.g.f.: exp(C(x) - 1) * C(x) / sqrt(1-4*x), where C(x) = (1 - sqrt(1-4*x))/(2*x) is the Catalan function (A000108). (End)

A006902 a(n) = (2n)! * Sum_{k=0..n} (-1)^k * binomial(n,k) / (n+k)!.

Original entry on oeis.org

1, 1, 5, 47, 641, 11389, 248749, 6439075, 192621953, 6536413529, 248040482741, 10407123510871, 478360626529345, 23903857657114837, 1290205338991689821, 74803882225482661259, 4636427218380366565889, 305927317398343461908785, 21410426012751471702223333
Offset: 0

Views

Author

Keywords

Comments

Number of words on {1,1,2,2,...,n,n} with longest increasing subsequence of length n. a(2) = 5: 1122, 1212, 1221, 2112, 2121. - Alois P. Heinz, Jan 18 2016

References

  • J. D. Horton and A. Kurn, Counting sequences with complete increasing subsequences, Congress. Numerantium, 33 (1981), 75-80.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Row n=2 of A047909.
Main diagonal of A267480.
Cf. A082545.

Programs

  • Magma
    [Factorial(n)*Evaluate(LaguerrePolynomial(n, n), 1): n in [0..40]]; // G. C. Greubel, Aug 11 2022
    
  • Maple
    a:= proc(n) option remember; `if`(n<3, [1$2, 5][n+1], (
          (n^3+n^2-7*n+4)*a(n-1)-2*(2*n-3)*(n-1)^3*a(n-2))/(n-2))
        end:
    seq(a(n), n=0..20);  # Alois P. Heinz, Jan 15 2016
  • Mathematica
    Table[(-1)^k HypergeometricU[-k, 1+k, 1], {k,0,20}] (* Vladimir Reshetnikov, Feb 16 2011 *)
  • PARI
    a(n)=round(hyperu(-n,n+1,1)*(-1)^n) \\ Charles R Greathouse IV, Dec 30 2014
    
  • 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). - Vladeta Jovovic, May 11 2003
(n-2)*a(n) - (n^3+n^2-7*n+4)*a(n-1) + 2*(2*n-3)*(n-1)^3*a(n-2) = 0. - Vladeta Jovovic, Jul 16 2004
a(n) ~ n^n*2^(2*n+1/2)/exp(n+1). - Vaclav Kotesovec, Jun 22 2013
a(n) = B_n(n*0!,(n-1)*1!, ..., 1*(n-1)!), where B_n(x1, ..., xn) is the n-th complete Bell polynomial. - Max Alekseyev, Jul 04 2015
a(n) = n!*binomial(2*n,n)*hypergeom([-n], [n+1], 1). - Peter Luschny, May 04 2017
a(n) = n!*Z(S_n; n, n-1, ..., 1) where Z(S_n) is the cycle index of the symmetric group of order n. - Sean A. Irvine, Nov 14 2017
a(n) = n! * [x^n] exp(-x/(1 - x))/(1 - x)^(n+1). - Ilya Gutkovskiy, Nov 21 2017
E.g.f.: exp(1-c(x))/sqrt(1-4*x), where c(x) = (1-sqrt(1-4*x))/(2*x) is the Catalan number generating function. - Ira M. Gessel, Jun 04 2021

Extensions

a(0)=1 prepended by Alois P. Heinz, Jan 15 2016

A295385 a(n) = n!*Sum_{k=0..n} binomial(2*n,n-k)*n^k/k!.

Original entry on oeis.org

1, 3, 32, 579, 14736, 483115, 19376928, 918980139, 50306339072, 3121729082739, 216541483852800, 16603614676249843, 1394473165806440448, 127308860552307549531, 12553171419275174137856, 1329537514269062031406875, 150531055969843353812533248, 18143286205523964035258551651
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 21 2017

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(n)*(&+[Binomial(2*n,n-k)*n^k/Factorial(k): k in [0..n]]): n in [0..30]]; // G. C. Greubel, Feb 06 2018
  • Mathematica
    Table[n! SeriesCoefficient[Exp[n x/(1 - x)]/(1 - x)^(n + 1), {x, 0, n}], {n, 0, 17}]
    Table[n! LaguerreL[n, n, -n], {n, 0, 17}]
    Table[(-1)^n HypergeometricU[-n, n + 1, -n], {n, 0, 17}]
    Join[{1}, Table[n! Sum[Binomial[2 n, n - k] n^k/k!, {k, 0, n}], {n, 1, 17}]]
  • PARI
    for(n=0,30, print1(n!*sum(k=0,n, binomial(2*n,n-k)*n^k/k!), ", ")) \\ G. C. Greubel, Feb 06 2018
    

Formula

a(n) = n! * [x^n] exp(n*x/(1 - x))/(1 - x)^(n+1).
a(n) = n!*Laguerre(n,n,-n).
a(n) ~ 2^(n - 1/2) * (1 + sqrt(2))^(n + 1/2) * n^n / exp((2 - sqrt(2))*n). - Vaclav Kotesovec, 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)

A343861 Coefficient triangle of generalized Laguerre polynomials n!*L(n,n,x) (rising powers of x).

Original entry on oeis.org

1, 2, -1, 12, -8, 1, 120, -90, 18, -1, 1680, -1344, 336, -32, 1, 30240, -25200, 7200, -900, 50, -1, 665280, -570240, 178200, -26400, 1980, -72, 1, 17297280, -15135120, 5045040, -840840, 76440, -3822, 98, -1, 518918400, -461260800, 161441280, -29352960, 3057600, -188160, 6720, -128, 1
Offset: 0

Views

Author

Seiichi Manyama, May 01 2021

Keywords

Examples

			The triangle begins:
       1;
       2,      -1;
      12,      -8,      1;
     120,     -90,     18,     -1;
    1680,   -1344,    336,    -32,    1;
   30240,  -25200,   7200,   -900,   50,  -1;
  665280, -570240, 178200, -26400, 1980, -72, 1;
		

Crossrefs

For k=0..1 the (unsigned) columns give A001813, A092956(n-1).
Row sums (signed) give A006902, row sums (unsigned) give A082545.

Programs

  • Magma
    [(-1)^k*Factorial(n-k)*Binomial(n,k)*Binomial(2*n, n+k): k in [0..n], n in [0..12]]; // G. C. Greubel, Aug 11 2022
    
  • Mathematica
    T[n_, k_] := (-1)^k * (2*n)! * Binomial[n, k]/(k + n)!; Table[T[n, k], {n, 0, 8}, {k, 0, n}] // Flatten (* Amiram Eldar, May 11 2021 *)
  • PARI
    T(n, k) = (-1)^k*(2*n)!*binomial(n,k)/(k+n)!;
    
  • PARI
    row(n) = Vecrev(n!*pollaguerre(n, n));
    
  • SageMath
    def A343861(n,k): return (-1)^k*factorial(n-k)*binomial(n,k)*binomial(2*n,n+k)
    flatten([[A343861(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Aug 11 2022

Formula

T(n, k) = (-1)^k * n! * binomial(2*n,n-k)/k! = (-1)^k * (2*n)! * binomial(n,k)/(k+n)!.
T(n, 0) = A001813(n).
T(n, 1) = -A092956(n-1).
Sum_{k=0..n} T(n, k) = A006902(n).
Sum_{k=0..n} (-1)^k * T(n, k) = A082545(n).

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).

A253670 Square array read by ascending antidiagonals, T(n, k) = k!*[x^k](exp(x)*sum(j=0..n, C(2*n,j)*x^j)), n>=0, k>=0.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 5, 5, 1, 1, 7, 21, 7, 1, 1, 9, 43, 49, 9, 1, 1, 11, 73, 229, 89, 11, 1, 1, 13, 111, 529, 685, 141, 13, 1, 1, 15, 157, 1021, 3393, 1531, 205, 15, 1, 1, 17, 211, 1753, 8501, 12361, 2887, 281, 17, 1, 1, 19, 273, 2773, 18001, 63591, 32809, 4873, 369, 19, 1
Offset: 0

Views

Author

Peter Luschny, Jan 18 2015

Keywords

Examples

			Square array starts:
[n\k][0   1    2     3      4       5        6]
[0]   1,  1,   1,    1,     1,      1,       1, ...
[1]   1,  3,   5,    7,     9,     11,      13, ...
[2]   1,  5,  21,   49,    89,    141,     205, ...
[3]   1,  7,  43,  229,   685,   1531,    2887, ...
[4]   1,  9,  73,  529,  3393,  12361,   32809, ...
[5]   1, 11, 111, 1021,  8501,  63591,  272851, ...
[6]   1, 13, 157, 1753, 18001, 169021, 1442173, ...
The first few rows as a triangle:
1
1,  1
1,  3,  1
1,  5,  5,   1
1,  7, 21,   7,  1
1,  9, 43,  49,  9,  1
1, 11, 73, 229, 89, 11, 1
		

Crossrefs

Cf. A082545.

Programs

  • Maple
    T := (n,k) -> k!*coeff(series(exp(x)*add(binomial(2*n,j)*x^j,j=0..n), x, k+1), x, k): for n from 0 to 6 do lprint(seq(T(n,k), k=0..6)) od;

Formula

T(n,n) = A082545(n).
Showing 1-10 of 10 results.