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.

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A131182 Table T(n,k) = n!*k^n, read by upwards antidiagonals.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 2, 1, 0, 6, 8, 3, 1, 0, 24, 48, 18, 4, 1, 0, 120, 384, 162, 32, 5, 1, 0, 720, 3840, 1944, 384, 50, 6, 1, 0, 5040, 46080, 29160, 6144, 750, 72, 7, 1, 0, 40320, 645120, 524880, 122880, 15000, 1296, 98, 8, 1, 0, 362880, 10321920, 11022480, 2949120, 375000, 31104, 2058, 128, 9, 1
Offset: 0

Views

Author

Philippe Deléham, Sep 25 2007

Keywords

Comments

For k>0, T(n,k) is the n-th moment of the exponential distribution with mean = k. - Geoffrey Critzer, Jan 06 2019
T(n,k) is the minimum value of Product_{i=1..n} Sum_{j=1..k} r_j[i] where each r_j is a permutation of {1..n}. For the maximum value, see A331988. - Chai Wah Wu, Sep 01 2022

Examples

			The (inverted) table begins:
k=0: 1, 0,   0,    0,      0,       0, ... (A000007)
k=1: 1, 1,   2,    6,     24,     120, ... (A000142)
k=2: 1, 2,   8,   48,    384,    3840, ... (A000165)
k=3: 1, 3,  18,  162,   1944,   29160, ... (A032031)
k=4: 1, 4,  32,  384,   6144,  122880, ... (A047053)
k=5: 1, 5,  50,  750,  15000,  375000, ... (A052562)
k=6: 1, 6,  72, 1296,  31104,  933120, ... (A047058)
k=7: 1, 7,  98, 2058,  57624, 2016840, ... (A051188)
k=8: 1, 8, 128, 3072,  98304, 3932160, ... (A051189)
k=9: 1, 9, 162, 4374, 157464, 7085880, ... (A051232)
Main diagonal is 1, 1, 8, 162, 6144, 375000, ... (A061711).
		

Crossrefs

Main diagonal gives A061711.

Programs

  • Maple
    T:= (n,k)-> n!*k^n:
    seq(seq(T(d-k, k), k=0..d), d=0..12);  # Alois P. Heinz, Jan 06 2019
  • Python
    from math import factorial
    def A131182_T(n, k): # compute T(n, k)
        return factorial(n)*k**n # Chai Wah Wu, Sep 01 2022

Formula

From Ilya Gutkovskiy, Aug 11 2017: (Start)
G.f. of column k: 1/(1 - k*x/(1 - k*x/(1 - 2*k*x/(1 - 2*k*x/(1 - 3*k*x/(1 - 3*k*x/(1 - ...))))))), a continued fraction.
E.g.f. of column k: 1/(1 - k*x). (End)

A153271 Triangle T(n, k) = Product_{j=0..k} (j*n + prime(m)), with T(n, 0) = prime(m) and m = 3, read by rows.

Original entry on oeis.org

5, 5, 30, 5, 35, 315, 5, 40, 440, 6160, 5, 45, 585, 9945, 208845, 5, 50, 750, 15000, 375000, 11250000, 5, 55, 935, 21505, 623645, 21827575, 894930575, 5, 60, 1140, 29640, 978120, 39124800, 1838865600, 99298742400, 5, 65, 1365, 39585, 1464645, 65909025, 3493178325, 213083877825, 14702787569925
Offset: 0

Views

Author

Roger L. Bagula, Dec 22 2008

Keywords

Comments

Row sums are {5, 35, 355, 6645, 219425, 11640805, 917404295, 101177741765, 14919432040765, 2839006665525525, 677815000136926955, ...}.

Examples

			Triangle begins as:
  5;
  5, 30;
  5, 35, 315;
  5, 40, 440,  6160;
  5, 45, 585,  9945, 208845;
  5, 50, 750, 15000, 375000, 11250000;
  5, 55, 935, 21505, 623645, 21827575, 894930575;
		

Crossrefs

Cf. A153271 (m=2), this sequence (m=3), A153272 (m=4).
Sequences related to m values:

Programs

  • Magma
    m:=3;
    function T(n,k)
      if k eq 0 then return NthPrime(m);
      else return (&*[j*n + NthPrime(m): j in [0..k]]);
      end if; return T; end function;
    [T(n,k): k in [0..n], n in [0..10]]; // G. C. Greubel, Dec 03 2019
    
  • Maple
    m:=3; seq(seq(`if`(k=0, ithprime(m), mul(j*n + ithprime(m), j=0..k)), k=0..n), n=0..10); # G. C. Greubel, Dec 03 2019
  • Mathematica
    T[n_, k_, m_]:= If[k==0, Prime[m], Product[j*n + Prime[m], {j,0,k}]];
    Table[T[n,k,3], {n,0,10}, {k,0,n}]//Flatten
  • PARI
    T(n,k) = my(m=3); if(k==0, prime(m), prod(j=0,k, j*n + prime(m)) ); \\ G. C. Greubel, Dec 03 2019
    
  • Sage
    def T(n, k):
        m=3
        if (k==0): return nth_prime(m)
        else: return product(j*n + nth_prime(m) for j in (0..k))
    [[T(n, k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Dec 03 2019

Formula

T(n, k) = Product_{j=0..k} (j*n + prime(m)), with T(n, 0) = prime(m) and m = 3.

Extensions

Edited by G. C. Greubel, Dec 03 2019

A196258 a(n) = 11^n*n!.

Original entry on oeis.org

1, 11, 242, 7986, 351384, 19326120, 1275523920, 98215341840, 8642950081920, 855652058110080, 94121726392108800, 11388728893445164800, 1503312213934761753600, 214973646592670930764800, 33105941575271323337779200
Offset: 0

Views

Author

Philippe Deléham, Oct 27 2011

Keywords

Crossrefs

Programs

Formula

a(n) = 11^n*n!.
E.g.f.: 1/(1-11*x).
From Amiram Eldar, Jun 25 2020: (Start)
Sum_{n>=0} 1/a(n) = e^(1/11).
Sum_{n>=0} (-1)^n/a(n) = e^(-1/11). (End)

A052675 Expansion of e.g.f. (1-x)/(1-5*x).

Original entry on oeis.org

1, 4, 40, 600, 12000, 300000, 9000000, 315000000, 12600000000, 567000000000, 28350000000000, 1559250000000000, 93555000000000000, 6081075000000000000, 425675250000000000000, 31925643750000000000000
Offset: 0

Views

Author

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

Keywords

Crossrefs

Programs

  • Maple
    spec := [S,{S=Sequence(Prod(Sequence(Z),Union(Z,Z,Z,Z)))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
  • Mathematica
    Table[(4/5)*(5^n*n! + Boole[n==0]/4), {n, 0, 50}] (* G. C. Greubel, Jun 12 2022 *)
    With[{nn=20},CoefficientList[Series[(1-x)/(1-5x),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Jul 31 2023 *)
  • SageMath
    [4*factorial(n)*5^(n-1) + bool(n==0)/5 for n in (0..40)] # G. C. Greubel, Jun 12 2022

Formula

E.g.f.: (1 - x)/(1 - 5*x).
D-finite Recurrence: a(0)=1, a(1)=4, a(n) = 5*n*a(n-1).
a(n) = 4*5^(n-1)*n!, n>0.
a(n) = (4/5) * A052562(n).
a(n) = n!*A005054(n). - R. J. Mathar, Jun 03 2022
G.f.: (4/5)*(Hypergeometric2F0([1, 1], [], 5*x) + 1/4). - G. C. Greubel, Jun 12 2022
Previous Showing 21-24 of 24 results.