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 1-8 of 8 results.

A047909 Array read by antidiagonals upwards: h(n,k) = number of sequences with n copies each of 1,2,...,k and longest increasing subsequence of length k (n>=1, k>=1).

Original entry on oeis.org

1, 1, 1, 1, 5, 1, 1, 19, 47, 1, 1, 69, 1306, 641, 1, 1, 251, 31451, 195709, 11389, 1, 1, 923, 729811, 46922017, 50775091, 248749, 1, 1, 3431, 16928840, 10258694241, 162588279629, 20117051281, 6439075, 1, 1, 12869, 397222288, 2176464012941, 449363984934526, 1077273394836829, 11260558754404, 192621953, 1
Offset: 1

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Author

Keywords

Comments

Old name was: Triangle of numbers arising from problem of complete increasing subsequences.
Table h_p(k) on page 80 in the Horton & Kurn reference has two typos. - Alois P. Heinz, Feb 05 2016
Conjecture: Column k > 1 is asymptotic to k^(k*n + 1/2) / (2*Pi*n)^((k-1)/2). - Vaclav Kotesovec, Feb 21 2016
Conjecture: Row k > 1 is asymptotic to sqrt(k) * (k^k/(k-1)!)^n * n^((k-1)*n) / exp((k-1)*(n+1)). - Vaclav Kotesovec, Feb 21 2016

Examples

			First few antidiagonals are:
  1;
  1,   1;
  1,   5,      1;
  1,  19,     47,        1;
  1,  69,   1306,      641,        1;
  1, 251,  31451,   195709,    11389,      1;
  1, 923, 729811, 46922017, 50775091, 248749,   1;
  ...
First few rows are:
  1,   1,        1,             1,                   1, ...
  1,   5,       47,           641,               11389, ...
  1,  19,     1306,        195709,            50775091, ...
  1,  69,    31451,      46922017,        162588279629, ...
  1, 251,   729811,   10258694241,     449363984934526, ...
  1, 923, 16928840, 2176464012941, 1162145520205261219, ...
  ...
		

Crossrefs

Main diagonal gives A268485.

Programs

  • Maple
    g:= proc(l) option remember; (n-> f(l[1..nops(l)-1])*
          binomial(n-1, l[-1]-1)+ add(f(sort(subsop(j=l[j]
          -1, l))), j=1..nops(l)-1))(add(i, i=l))
        end:
    f:= l-> (n-> `if`(n<2 or l[-1]=1, 1, `if`(l[1]=0, 0, `if`(
             n=2, binomial(l[1]+l[2], l[1])-1, g(l)))))(nops(l)):
    h:= (n, k)-> f([n$k]):
    seq(seq(h(1+d-k, k), k=1..d), d=1..10);  # Alois P. Heinz, Feb 11 2016
    # second Maple program:
    b:= proc(k, p, j, l, t) option remember;
          `if`(k=0, (-1)^t/l!, `if`(p<0, 0, add(b(k-i, p-1,
           j+1, l+i*j, irem(t+i*j, 2))/(i!*p!^i), i=0..k)))
        end:
    h:= (p, k)-> k!*(p*k)!*b(k, p-1, 1, 0, irem(k, 2)):
    seq(seq(h(1+d-k, k), k=1..d), d=1..10);  # Alois P. Heinz, Mar 03 2016
  • Mathematica
    g[l_] := g[l] = Function[n, f[l[[1 ;; -2]]]*Binomial[n-1, l[[-1]]-1] + Sum[ f[Sort[ReplacePart[l, j -> l[[j]] - 1]]], {j, 1, Length[l] -1}]][ Total[ l]]; f[l_] := Function [n, If[n<2 || l[[-1]]==1, 1, If[l[[1]]==0, 0, If[n == 2, Binomial[l[[1]] + l[[2]], l[[1]] ] - 1, g[l]]]]][Length[l]]; h[n_, k_] := f[Array[n&, k]]; Table[Table[h[1+d-k, k], {k, 1, d}], {d, 1, 10}] // Flatten (* Jean-François Alcover, Feb 19 2016, after Alois P. Heinz *)

Formula

Reference gives explicit formula.

Extensions

New name, two terms corrected and more terms from Alois P. Heinz, Feb 08 2016

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

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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

A267480 Number T(n,k) of words on {1,1,2,2,...,n,n} with longest increasing subsequence of length k; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 5, 0, 1, 42, 47, 0, 1, 351, 1527, 641, 0, 1, 3113, 43910, 54987, 11389, 0, 1, 29003, 1302660, 3844840, 2059147, 248749, 0, 1, 280220, 40970298, 265777225, 285588543, 82025038, 6439075, 0, 1, 2782475, 1364750889, 19104601915, 37783672691, 19773928713, 3507289363, 192621953
Offset: 0

Views

Author

Alois P. Heinz, Jan 15 2016

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1,      5;
  0, 1,     42,       47;
  0, 1,    351,     1527,       641;
  0, 1,   3113,    43910,     54987,     11389;
  0, 1,  29003,  1302660,   3844840,   2059147,   248749;
  0, 1, 280220, 40970298, 265777225, 285588543, 82025038, 6439075;
		

Crossrefs

Main diagonal gives A006902.
Row sums give A000680.

Formula

T(n,0) = A267479(n,0), T(n,k) = A267479(n,k) - A267479(n,k-1) for k>0.
Sum_{k=0..n-1} T(n,k) = A267532(n).

A267532 Number of words on {1,1,2,2,...,n,n} with longest increasing subsequence of length < n.

Original entry on oeis.org

0, 0, 1, 43, 1879, 102011, 7235651, 674641325, 81537026047, 12498099730471, 2375632826877259, 548818073236649129, 151476182218777630655, 49229890784448694885163, 18608906461974462064310179, 8094874797394331233877338741, 4015057931973886657462193434111
Offset: 0

Views

Author

Alois P. Heinz, Jan 16 2016

Keywords

Comments

Or number of words on {1,1,2,2,...,n,n} avoiding the pattern 12...n.

Examples

			a(2) = 1: 2211.
a(3) = 43: 113322, 131322, 133122, 133212, 133221, 211332, 213132, 213312, 213321, 221133, 221313, 221331, 223113, 223131, 223311, 231132, 231312, 231321, 232113, 232131, 232311, 233112, 233121, 233211, 311322, 313122, 313212, 313221, 321132, 321312, 321321, 322113, 322131, 322311, 323112, 323121, 323211, 331122, 331212, 331221, 332112, 332121, 332211.
		

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<3, [1$2, 5][n+1], (
          (n^3+n^2-7*n+4)*b(n-1)-2*(2*n-3)*(n-1)^3*b(n-2))/(n-2))
        end:
    a:= n-> (2*n)!/(2^n)-b(n):
    seq(a(n), n=0..20);

Formula

a(n) = (2*n)! * ( 1/(2^n) - Sum_{k=0..n} (-1)^k * C(n,k) / (n+k)! ).
a(n) = A000680(n) - A006902(n).
a(n) = A267479(n,n-1) for n>0.
a(n) = Sum_{k=0..n-1} A267480(n,k).

A295384 a(n) = n!*Sum_{k=0..n} (-1)^k*binomial(2*n,n-k)*n^k/k!.

Original entry on oeis.org

1, 1, 0, -15, -112, -135, 9504, 152425, 610560, -27692847, -765107200, -6289891839, 213472972800, 9380264146825, 129378550468608, -3294028613874375, -226623617585053696, -4707649131227927775, 83803818828756418560, 9446689798312021406353, 277055229100887244800000
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 21 2017

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(n)*(&+[(-1)^k*Binomial(2*n,n-k)*n^k/Factorial(k): k in [0..n]]): n in [0..30]]; // G. C. Greubel, Feb 06 2018
  • Maple
    a := n -> pochhammer(n, n)*hypergeom([1 - n], [n], n):
    seq(simplify(a(n)), n = 0..20); # Peter Luschny, Mar 23 2023
  • Mathematica
    Table[n! SeriesCoefficient[Exp[-n x/(1 - x)]/(1 - x)^(n + 1), {x, 0, n}], {n, 0, 20}]
    Table[n! LaguerreL[n, n, n], {n, 0, 20}]
    Table[(-1)^n HypergeometricU[-n, n + 1, n], {n, 0, 20}]
    Join[{1}, Table[n! Sum[(-1)^k Binomial[2 n, n - k] n^k/k!, {k, 0, n}], {n, 1, 20}]]
  • PARI
    for(n=0,30, print1(n!*sum(k=0,n, (-1)^k*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) = Pochhammer(n, n)*hypergeom([1 - n], [n], n). - Peter Luschny, Mar 23 2023

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).

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

A358112 Table read by rows. A statistic of permutations of the multiset {1,1,2,2,...,n,n}.

Original entry on oeis.org

1, 5, 1, 47, 42, 1, 641, 1659, 219, 1, 11389, 72572, 28470, 968, 1, 248749, 3610485, 3263402, 357746, 4017, 1, 6439075, 204023334, 371188155, 95559940, 3853617, 16278, 1, 192621953, 12989570167, 43844432805, 22448025251, 2216662051, 38270373, 65399, 1
Offset: 1

Views

Author

Peter Luschny, Oct 30 2022

Keywords

Comments

Table 1, page 12 in Maazouz and Pitman (note a typo in T(2, 0)).

Examples

			[n\d]    0            1           2           3           4           5     6
-----------------------------------------------------------------------------
[1]         1;
[2]         5,           1;
[3]        47,          42,           1;
[4]       641,        1659,         219,           1;
[5]     11389,       72572,       28470,         968,          1;
[6]    248749,     3610485,     3263402,      357746,       4017,        1;
[7]   6439075,   204023334,   371188155,    95559940,    3853617,    16278, 1
[8] 192621953, 12989570167, 43844432805, 22448025251, 2216662051, 38270373,
65399, 1
		

Crossrefs

Cf. A006902 (row 0), A000680 (row sums).

Programs

  • Maple
    P := (n, x) -> (2*n)!*add(add(binomial(n, k)*binomial(n-k, j)*
    (-1)^(n-k-j)*max(x - k, 0)^(2*n - j)/(2*n - j)!, j = 0..n-k), k = 0..n):
    Trow := n -> seq(P(n, k+1) - P(n, k), k = 0..n-1):
    seq(print(Trow(n)), n = 1..8);

Formula

T(n, k) = P(n, k+1) - P(n, k), where P(n, x) = (2*n)!*Sum_{k=0..n} Sum_{j=0..n-k} binomial(n, k)*binomial(n-k, j)*(-1)^(n-k-j)*max(x - k, 0)^(2*n - j)/(2*n - j)!.
Showing 1-8 of 8 results.