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 11-16 of 16 results.

A111941 Matrix log of triangle A111940, which shifts columns left and up under matrix inverse; these terms are the result of multiplying each element in row n and column k by (n-k)!.

Original entry on oeis.org

0, 1, 0, -1, -1, 0, 1, 1, 1, 0, -2, -1, -1, -1, 0, 4, 2, 1, 1, 1, 0, -12, -4, -2, -1, -1, -1, 0, 36, 12, 4, 2, 1, 1, 1, 0, -144, -36, -12, -4, -2, -1, -1, -1, 0, 576, 144, 36, 12, 4, 2, 1, 1, 1, 0, -2880, -576, -144, -36, -12, -4, -2, -1, -1, -1, 0, 14400, 2880, 576, 144, 36, 12, 4, 2, 1, 1, 1, 0, -86400, -14400, -2880, -576, -144, -36
Offset: 0

Views

Author

Paul D. Hanna, Aug 23 2005

Keywords

Examples

			Triangle begins:
0;
1, 0;
-1, -1, 0;
1, 1, 1, 0;
-2, -1, -1, -1, 0;
4, 2, 1, 1, 1, 0;
-12, -4, -2, -1, -1, -1, 0;
36, 12, 4, 2, 1, 1, 1, 0;
-144, -36, -12, -4, -2, -1, -1, -1, 0;
576, 144, 36, 12, 4, 2, 1, 1, 1, 0;
-2880, -576, -144, -36, -12, -4, -2, -1, -1, -1, 0;
14400, 2880, 576, 144, 36, 12, 4, 2, 1, 1, 1, 0;
-86400, -14400, -2880, -576, -144, -36, -12, -4, -2, -1, -1, -1, 0;
518400, 86400, 14400, 2880, 576, 144, 36, 12, 4, 2, 1, 1, 1, 0;
-3628800, -518400, -86400, -14400, -2880, -576, -144, -36, -12, -4, -2, -1, -1, -1, 0; ...
where, apart from signs, the columns are all the same (A111942).
...
Triangle A111940 begins:
1;
1, 1;
-1, -1, 1;
0, 0, 1, 1;
0, 0, -1, -1, 1;
0, 0, 0, 0, 1, 1;
0, 0, 0, 0, -1, -1, 1;
0, 0, 0, 0, 0, 0, 1 ,1;
0, 0, 0, 0, 0, 0, -1, -1, 1; ...
where the matrix inverse shifts columns left and up one place.
...
The matrix log of A111940, with factorial denominators, begins:
0;
1/1!, 0;
-1/2!, -1/1!, 0;
1/3!, 1/2!, 1/1!, 0;
-2/4!, -1/3!, -1/2!, -1/1!, 0;
4/5!, 2/4!, 1/3!, 1/2!, 1/1!, 0;
-12/6!, -4/5!, -2/4!, -1/3!, -1/2!, -1/1!, 0;
36/7!, 12/6!, 4/5!, 2/4!, 1/3!, 1/2!, 1/1!, 0;
-144/8!, -36/7!, -12/6!, -4/5!, -2/4!, -1/3!, -1/2!, -1/1!, 0;
576/9!, 144/8!, 36/7!, 12/6!, 4/5!, 2/4!, 1/3!, 1/2!, 1/1!, 0;
-2880/10!, -576/9!, -144/8!, -36/7!, -12/6!, -4/5!, -2/4!, -1/3!, -1/2!, -1/1!, 0;
14400/11!, 2880/10!, 576/9!, 144/8!, 36/7!, 12/6!, 4/5!, 2/4!, 1/3!, 1/2!, 1/1!, 0; ...
Note that the square of the matrix log of A111940 begins:
0;
0, 0;
-1, 0, 0;
0, -1, 0, 0;
-1/12, 0, -1, 0, 0;
0, -1/12, 0, -1, 0, 0;
-1/90, 0, -1/12, 0, -1, 0, 0;
0, -1/90, 0, -1/12, 0, -1, 0, 0;
-1/560, 0, -1/90, 0, -1/12, 0, -1, 0, 0;
0, -1/560, 0, -1/90, 0, -1/12, 0, -1, 0, 0;
-1/3150, 0, -1/560, 0, -1/90, 0, -1/12, 0, -1, 0, 0;
0, -1/3150, 0, -1/560, 0, -1/90, 0, -1/12, 0, -1, 0, 0;
-1/16632, 0, -1/3150, 0, -1/560, 0, -1/90, 0, -1/12, 0, -1, 0, 0; ...
where nonzero terms are negative unit fractions with denominators given by A002544:
[1, 12, 90, 560, 3150, 16632, 84084, 411840, ...,  C(2*n+1,n)*(n+1)^2, ...].
		

Crossrefs

Cf. A111940 (triangle), A111942 (column 0), A110504 (variant).

Programs

  • PARI
    {T(n,k,q=-1) = local(A=Mat(1),B); if(n
    				

Formula

T(n, k) = (-1)^k*T(n-k, 0) = (-1)^k*A111942(n-k) for n>=k>=0.

A175478 Decimal expansion of log(3)^2.

Original entry on oeis.org

1, 2, 0, 6, 9, 4, 8, 9, 6, 0, 8, 1, 2, 5, 8, 1, 9, 7, 7, 8, 4, 3, 7, 7, 9, 1, 2, 3, 8, 4, 9, 3, 6, 5, 9, 1, 3, 6, 1, 8, 4, 6, 3, 3, 4, 6, 6, 2, 9, 2, 2, 1, 9, 8, 4, 8, 1, 6, 7, 2, 6, 8, 4, 0, 0, 5, 8, 2, 1, 5, 5, 1, 4, 8, 0, 7, 9, 8, 5, 2, 5, 4, 4, 5, 8, 5, 4, 4, 3, 0, 1, 7, 7, 1, 4, 0, 9, 3, 3, 3, 4, 2, 2, 8, 3
Offset: 1

Views

Author

R. J. Mathar, May 25 2010

Keywords

Examples

			1.2069489608125819778437...
		

Crossrefs

Programs

Formula

Equals A002391^2.
Equals Sum_{n >= 0} (-1)^n*(4/3)^(n+1)/((n+1)^2*binomial(2*n+1,n)). See my entry in A002544 dated Apr 18 2017. - Peter Bala, Jan 30 2023

A245111 G.f.: A(x,y) = Sum_{n>=0} exp(-y/(1-n*x)) * y^n/(1-n*x)^n / n!.

Original entry on oeis.org

1, 0, 1, 0, 1, 3, 0, 1, 12, 10, 0, 1, 35, 90, 35, 0, 1, 90, 525, 560, 126, 0, 1, 217, 2520, 5460, 3150, 462, 0, 1, 504, 10836, 42000, 46200, 16632, 1716, 0, 1, 1143, 43470, 280665, 519750, 342342, 84084, 6435, 0, 1, 2550, 166375, 1709400, 4969965, 5297292, 2312310, 411840, 24310
Offset: 0

Views

Author

Paul D. Hanna, Jul 12 2014

Keywords

Comments

Compare g.f. to: 1/(1-x*y) = Sum_{n>=0} exp(-y*(1+n*x)) * y^n*(1+n*x)^n / n!.
Row sums equal A245110.
Antidiagonal sums: A218667.
Main diagonal is: C(2*n-1,n) (A001700).
Secondary diagonal: C(2*n-1,n)*n^2 (A002544).

Examples

			G.f.: A(x,y) = 1 + x*y + x^2*(y + 3*y^2)
+ x^3*(y + 12*y^2 + 10*y^3)
+ x^4*(y + 35*y^2 + 90*y^3 + 35*y^4)
+ x^5*(y + 90*y^2 + 525*y^3 + 560*y^4 + 126*y^5)
+ x^6*(y + 217*y^2 + 2520*y^3 + 5460*y^4 + 3150*y^5 + 462*y^6) +...
where
A(x,y) = exp(-y) + exp(-y/(1-x))*y/(1-x) + (exp(-y/(1-2*x))*y^2/(1-2*x)^2)/2!
+ (exp(-y/(1-3*x))*y^3/(1-3*x)^3)/3! + (exp(-y/(1-4*x))*y^4/(1-4*x)^4)/4!
+ (exp(-y/(1-5*x))*y^5/(1-5*x)^5)/5! + (exp(-y/(1-6*x))*y^6/(1-6*x)^6)/6!
+ (exp(-y/(1-7*x))*y^7/(1-7*x)^7)/7! + (exp(-y/(1-8*x))*y^8/(1-8*x)^8)/8! +...
simplifies to a power series with only integer coefficients of x^n*y^k.
Triangle begins:
1;
0, 1;
0, 1, 3;
0, 1, 12, 10;
0, 1, 35, 90, 35;
0, 1, 90, 525, 560, 126;
0, 1, 217, 2520, 5460, 3150, 462;
0, 1, 504, 10836, 42000, 46200, 16632, 1716;
0, 1, 1143, 43470, 280665, 519750, 342342, 84084, 6435;
0, 1, 2550, 166375, 1709400, 4969965, 5297292, 2312310, 411840, 24310;
0, 1, 5621, 615780, 9754030, 42567525, 68549481, 47087040, 14586000, 1969110, 92378; ...
where T(n,k) = A048993(n,k) * C(n+k-1, k-1) for k>0.
		

Crossrefs

Programs

  • PARI
    /* From definition: */
    {T(n,k)=local(A=1+x*y); A=sum(k=0, n, 1/(1-k*x+x*O(x^n))^k*y^k/k!*exp(-y/(1-k*x+x*O(x^n))+y*O(y^n))); polcoeff(polcoeff(A, n,x),k,y)}
    for(n=0, 10, for(k=0,n, print1(T(n,k),", "));print(""))
    
  • PARI
    /* From T(n,k) = Stirling2(n, k) * C(n+k-1, k-1) */
    {Stirling2(n, k) = sum(j=0, k, (-1)^(k+j) * binomial(k, j) * j^n) / k!}
    {T(n,k)=if(k==0,0^n,Stirling2(n, k) * binomial(n+k-1, k-1))}
    for(n=0, 10, for(k=0,n, print1(T(n,k),", "));print(""))

Formula

T(n,k) = Stirling2(n, k) * binomial(n+k-1, k-1) for k>0, where Stirling2(n,k) = A048993(n,k).

A106440 a(n) = binomial(2n+4,n)*binomial(n+4,4).

Original entry on oeis.org

1, 30, 420, 4200, 34650, 252252, 1681680, 10501920, 62355150, 355655300, 1963217256, 10546208400, 55367594100, 285028443000, 1442592936000, 7193730107520, 35406640372950, 172255143129300, 829376615067000
Offset: 0

Views

Author

Paul Barry, May 02 2005

Keywords

Comments

Fifth column of A104684.
Diagonal of the rational function 1 / (1 - x - y)^5. - Ilya Gutkovskiy, Apr 24 2025

Crossrefs

Programs

  • Mathematica
    Table[Binomial[2n+4,n]Binomial[n+4,4],{n,0,20}] (* Harvey P. Dale, May 03 2019 *)

Formula

G.f.: (1+12x+6x^2)/(1-4x)^(9/2).
D-finite with recurrence n^2*a(n) -2*(n+2)*(2*n+3)*a(n-1)=0. - R. J. Mathar, Feb 20 2015
G.f.: 2F1(5/2,3;1;4x). - R. J. Mathar, Aug 09 2015
a(n) = A020920(n)+12*A020920(n-1)+6*A020920(n-2). - R. J. Mathar, Aug 09 2015
a(n) = (n+1)*A002803(n). - R. J. Mathar, Aug 09 2015

A349427 a(n) = ((n+1)^2 - 2) * binomial(2*n-2,n-1) / 2.

Original entry on oeis.org

0, 1, 7, 42, 230, 1190, 5922, 28644, 135564, 630630, 2892890, 13117676, 58903572, 262303132, 1159666900, 5094808200, 22259364120, 96773942790, 418882316490, 1805951924700, 7758285404100, 33221013445620, 141830949914940, 603876402587640, 2564713671647400
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 17 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((n + 1)^2 - 2) Binomial[2 n - 2, n - 1]/2, {n, 0, 24}]
    nmax = 24; CoefficientList[Series[x (1 - x) (1 - 2 x)/(1 - 4 x)^(5/2), {x, 0, nmax}], x]
  • PARI
    a(n) = ((n+1)^2 - 2) * binomial(2*n-2,n-1) / 2 \\ Andrew Howroyd, Nov 20 2021

Formula

G.f.: x * (1 - x) * (1 - 2*x) / (1 - 4*x)^(5/2).
E.g.f.: x * exp(2*x) * (2 * (1 + x) * BesselI(0,2*x) + (1 + 2*x) * BesselI(1,2*x)) / 2.
a(n) = n * ((n+1)^2 - 2) * Catalan(n-1) / 2.
a(n) = Sum_{k=0..n} binomial(n,k)^2 * A000217(k).
a(n) ~ 2^(2*n-3) * n^(3/2) / sqrt(Pi).
D-finite with recurrence (n-1)*(n^2-2)*a(n) -2*(2*n-3)*(n^2+2*n-1)*a(n-1)=0. - R. J. Mathar, Mar 06 2022

A228080 (5*n+2)!/(2*(n!)^5), n >= 0.

Original entry on oeis.org

1, 2520, 7484400, 22870848000, 70579794285000, 218799620836917120, 679953587124305894400, 2116187746296592370688000, 6592431144164903462359935000, 20550499897066845200729434200000, 64091912654977017603465324370118400, 199956261330234671205699024876891648000
Offset: 0

Views

Author

Karol A. Penson, Aug 09 2013

Keywords

Comments

Although limit( a(n)^(1/n), n=infinity ) = 5^5, apparently this sequence is not a Hausdorff moment sequence of any positive function on (0,5^5).

Crossrefs

Cf. A002544.

Programs

  • Maple
    seq((5*n+2)!/(2*(n!)^5), n=0..11).
  • Mathematica
    Table[(5n+2)!/(2(n!)^5),{n,0,15}] (* Harvey P. Dale, Aug 04 2019 *)

Formula

In Maple notation:
O.g.f. : hypergeom([3/5, 4/5, 6/5, 7/5], [1, 1, 1], 5^5*z);
E.g.f. : hypergeom([3/5, 4/5, 6/5, 7/5], [1, 1, 1, 1], 5^5*z);
Asymptotics: a(n) -> (25*n^2+5*n-2)*(5^(5*n+1/2))* n^(-2)/(8*Pi^2), for n -> infinity.
D-finite with recurrence (n^4)*a(n) -5*(5*n+1)*(5*n+2)*(5*n-2)*(5*n-1)*a(n-1)=0. - R. J. Mathar, Jul 27 2022
Previous Showing 11-16 of 16 results.