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 11-17 of 17 results.

A051619 a(n) = (4*n+7)(!^4)/7(!^4), related to A034176(n+1) ((4*n+3)(!^4) quartic, or 4-factorials).

Original entry on oeis.org

1, 11, 165, 3135, 72105, 1946835, 60351885, 2112315975, 82380323025, 3542353890075, 166490632833525, 8491022274509775, 467006225098037625, 27553367280784219875, 1735862138689405852125, 116302763292190192092375
Offset: 0

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Author

Keywords

Comments

Row m=7 of the array A(5; m,n) := ((4*n+m)(!^4))/m(!^4), m >= 0, n >= 0.

Crossrefs

Cf. A047053, A007696(n+1), A000407, A034176(n+1), A034177(n+1), A051617-A051622 (rows m=0..10).

Programs

  • Magma
    m:=30; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(1/(1-4*x)^(11/4))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Aug 15 2018
  • Mathematica
    s=1;lst={s};Do[s+=n*s;AppendTo[lst, s], {n, 10, 5!, 4}];lst (* Vladimir Joseph Stephan Orlovsky, Nov 08 2008 *)
    With[{nn = 30}, CoefficientList[Series[1/(1 - 4*x)^(11/4), {x, 0, nn}], x]*Range[0, nn]!] (* G. C. Greubel, Aug 15 2018 *)
  • PARI
    x='x+O('x^30); Vec(serlaplace(1/(1-4*x)^(11/4))) \\ G. C. Greubel, Aug 15 2018
    

Formula

a(n) = ((4*n+7)(!^4))/7(!^4) = A034176(n+2)/7.
E.g.f.: 1/(1-4*x)^(11/4).

A051621 a(n) = (4*n+9)(!^4)/9(!^4), related to A007696(n+1) ((4*n+1)(!^4) quartic, or 4-factorials).

Original entry on oeis.org

1, 13, 221, 4641, 116025, 3364725, 111035925, 4108329225, 168441498225, 7579867420125, 371413503586125, 19684915690064625, 1122040194333683625, 68444451854354701125, 4448889370533055573125, 306973366566780834545625
Offset: 0

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Author

Keywords

Comments

Row m=9 of the array A(5; m,n) := ((4*n+m)(!^4))/m(!^4), m >= 0, n >= 0.

Crossrefs

Cf. A047053, A007696(n+1), A000407, A034176(n+1), A034177(n+1), A051617-A051622 (rows m=0..10).

Programs

  • Magma
    m:=30; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(1/(1-4*x)^(13/4))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Aug 15 2018
  • Mathematica
    s=1;lst={s};Do[s+=n*s;AppendTo[lst, s], {n, 12, 5!, 4}];lst (* Vladimir Joseph Stephan Orlovsky, Nov 08 2008 *)
    With[{nn = 30}, CoefficientList[Series[1/(1 - 4*x)^(13/4), {x, 0, nn}], x]*Range[0, nn]!] (* G. C. Greubel, Aug 15 2018 *)
  • PARI
    x='x+O('x^30); Vec(serlaplace(1/(1-4*x)^(13/4))) \\ G. C. Greubel, Aug 15 2018
    

Formula

a(n) = ((4*n+9)(!^4))/9(!^4) = A007696(n+3)/(5*9).
E.g.f.: 1/(1-4*x)^(13/4).

A370915 A(n, k) = 4^n*Pochhammer(k/4, n). Square array read by ascending antidiagonals.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 5, 2, 1, 0, 45, 12, 3, 1, 0, 585, 120, 21, 4, 1, 0, 9945, 1680, 231, 32, 5, 1, 0, 208845, 30240, 3465, 384, 45, 6, 1, 0, 5221125, 665280, 65835, 6144, 585, 60, 7, 1, 0, 151412625, 17297280, 1514205, 122880, 9945, 840, 77, 8, 1
Offset: 0

Views

Author

Peter Luschny, Mar 06 2024

Keywords

Comments

The sequence of square arrays A(m, n, k) starts: A094587 (m = 1), A370419 (m = 2), A371077(m = 3), this array (m = 4).

Examples

			The array starts:
[0] 1,    1,     1,     1,      1,      1,      1,      1,      1, ...
[1] 0,    1,     2,     3,      4,      5,      6,      7,      8, ...
[2] 0,    5,    12,    21,     32,     45,     60,     77,     96, ...
[3] 0,   45,   120,   231,    384,    585,    840,   1155,   1536, ...
[4] 0,  585,  1680,  3465,   6144,   9945,  15120,  21945,  30720, ...
[5] 0, 9945, 30240, 65835, 122880, 208845, 332640, 504735, 737280, ...
.
Seen as the triangle T(n, k) = A(n - k, k):
[0] 1;
[1] 0,      1;
[2] 0,      1,     1;
[3] 0,      5,     2,    1;
[4] 0,     45,    12,    3,   1;
[5] 0,    585,   120,   21,   4,  1;
[6] 0,   9945,  1680,  231,  32,  5, 1;
[7] 0, 208845, 30240, 3465, 384, 45, 6, 1;
		

Crossrefs

Similar square arrays: A094587, A370419, A371077.
Cf. A370913 (row sums of triangle), A371026.

Programs

  • Maple
    A := (n, k) -> 4^n*pochhammer(k/4, n):
    for n from 0 to 5 do seq(A(n, k), k = 0..9) od;
    T := (n, k) -> A(n - k, k): seq(seq(T(n, k), k = 0..n), n = 0..9);
    # Using the exponential generating functions of the columns:
    EGFcol := proc(k, len) local egf, ser, n; egf := (1 - 4*x)^(-k/4);
    ser := series(egf, x, len+2): seq(n!*coeff(ser, x, n), n = 0..len) end:
    seq(lprint(EGFcol(n, 9)), n = 0..5);
    # Using the generating polynomials for the rows:
    P := (n, x) -> local k; add(Stirling1(n, k)*(-4)^(n - k)*x^k, k=0..n):
    seq(lprint([n], seq(P(n, k), k = 0..8)), n = 0..5);
    # Implementing the LU decomposition of A:
    with(LinearAlgebra):
    L := Matrix(7, 7, (n, k) -> A371026(n-1, k-1)):
    U := Matrix(7, 7, (n, k) -> binomial(n-1, k-1)):
    MatrixMatrixMultiply(L, Transpose(U));
  • Mathematica
    A[n_, k_] := 4^n * Pochhammer[k/4, n]; Table[A[n - k, k], {n, 0, 9}, {k, 0, n}] // Flatten (* Amiram Eldar, Mar 06 2024 *)
  • SageMath
    def A(n, k): return 4**n * rising_factorial(k/4, n)
    for n in range(6): print([A(n, k) for k in range(9)])

Formula

A(n, k) = 4^n*Product_{j=0..n-1} (j + k/4).
A(n, k) = 4^n*Gamma(k/4 + n) / Gamma(k/4) for k >= 1.
The exponential generating function for column k is (1 - 4*x)^(-k/4). But much more is true: (1 - m*x)^(-k/m) are the exponential generating functions for the columns of the arrays A(m, n, k) = m^n*Pochhammer(k/m, n).
The polynomials P(n, x) = Sum_{k=0..n} Stirling1(n, k)*(-4)^(n-k)*x^k are ordinary generating functions for row n, i.e., A(n, k) = P(n, k).
In A370419 Werner Schulte pointed out how A371025 is related to the LU decomposition of A370419. Here the same procedure can be used and amounts to A = A371026 * transpose(binomial triangle), where '*' denotes matrix multiplication. See the Maple section for an implementation.

A052570 E.g.f.: x/(1-4*x).

Original entry on oeis.org

0, 1, 8, 96, 1536, 30720, 737280, 20643840, 660602880, 23781703680, 951268147200, 41855798476800, 2009078326886400, 104472072998092800, 5850436087893196800, 351026165273591808000, 22465674577509875712000
Offset: 0

Views

Author

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

Keywords

Crossrefs

A034177 is an essentially identical sequence. - Philippe Deléham, Sep 18 2008

Programs

  • Maple
    spec := [S,{S=Prod(Z,Sequence(Union(Z,Z,Z,Z)))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
  • Mathematica
    With[{nn=20},CoefficientList[Series[x/(1-4x),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Jan 15 2017 *)

Formula

Recurrence: {a(1)=1, a(0)=0, (-4-4*n)*a(n)+a(n+1)=0.}
4^(n-1)*n!=n!*A000302(n-1). for n >= 1.

A081407 4th-order non-linear ("factorial") recursion: a(0)=a(1)=a(2)=a(3)=1, a(n) = (n+1)*a(n-4).

Original entry on oeis.org

1, 1, 1, 1, 5, 6, 7, 8, 45, 60, 77, 96, 585, 840, 1155, 1536, 9945, 15120, 21945, 30720, 208845, 332640, 504735, 737280, 5221125, 8648640, 13627845, 20643840, 151412625, 259459200, 422463195, 660602880, 4996616625, 8821612800
Offset: 0

Views

Author

Labos Elemer, Apr 01 2003

Keywords

Examples

			Following sequences are interleaved: A007696: {5,45,585,..}; A000404: {6,60,840,..} A034176: {7,77,1155,..}; A034177: {8,96,1536,..}
		

Crossrefs

Programs

  • GAP
    a:= function(k)
        if k<4 then return 1;
        elif k<7 then return k+1;
        else return (k+1)*a(k-4);
        fi;
      end;
    List([0..35], n-> a(n) ); # G. C. Greubel, Aug 24 2019
  • Haskell
    a081407 n = a081408_list !! n
    a081407_list = 1 : 1 : 1 : 1 : zipWith (*) [5..] a081407_list
    -- Reinhard Zumkeller, Jan 05 2012
    
  • Magma
    a:= func< n | n le 3 select 1 else n in [4..6] select n+1 else (n+1)*Self(n-3) >;
    [a(n): n in [0..35]]; // G. C. Greubel, Aug 24 2019
    
  • Mathematica
    f[n_]:= (n+1)*f[n-4]; f[0]=1; f[1]=1; f[2]=1; f[3]=1; Table[f[n], {n, 0, 40}]
    nxt[{n_,a_,b_,c_,d_}]:={n+1,b,c,d,a(n+2)}; NestList[nxt,{3,1,1,1,1},40][[;;,2]] (* Harvey P. Dale, Jan 13 2025 *)
  • PARI
    a(n) = if(n<4, 1, (n+1)*a(n-4) );
    vector(35, n, a(n-1)) \\ G. C. Greubel, Aug 24 2019
    
  • Sage
    def a(n):
        if n<4: return 1
        elif 4<= n <= 6: return n+1
        else: return (n+1)*a(n-4)
    [a(n) for n in (0..35)] # G. C. Greubel, Aug 24 2019
    

A098560 Expansion of e.g.f. (1+4*x)/(1-4*x).

Original entry on oeis.org

1, 8, 64, 768, 12288, 245760, 5898240, 165150720, 5284823040, 190253629440, 7610145177600, 334846387814400, 16072626615091200, 835776583984742400, 46803488703145574400, 2808209322188734464000, 179725396620079005696000
Offset: 0

Views

Author

Paul Barry, Sep 14 2004

Keywords

Crossrefs

Programs

  • Magma
    [1] cat [2^(2*n+1)*Factorial(n): n in [2..30]]; // G. C. Greubel, Jan 17 2018
  • Mathematica
    s=2;lst={1};Do[s+=n*s+s;AppendTo[lst, s], {n, 2, 5!, 4}];lst (* Vladimir Joseph Stephan Orlovsky, Nov 08 2008 *)
    With[{nn=20},CoefficientList[Series[(1+4x)/(1-4x),{x,0,nn}],x] Range[0,nn]!] (* or *) Join[{1},Table[2*4^n n!,{n,20}]] (* Harvey P. Dale, Jan 16 2012 *)
  • PARI
    for(n=0, 30, print1(if(n==0,1, 2^(2*n+1)*n!), ", ")) \\ G. C. Greubel, Jan 17 2018
    

Formula

a(n) = 2*4^n*n! - 0^n.
a(n+1) = 8*A034177(n).
a(n) - 4*n*a(n-1) = 0. - R. J. Mathar, Dec 21 2014
Sum_{n>=0} 1/a(n) = (exp(1/4)+1)/2. - Amiram Eldar, Feb 02 2023

A081408 a(n) = (n+1)*a(n-5), with a(0)=a(1)=a(2)=a(3)=a(4)=1.

Original entry on oeis.org

1, 1, 1, 1, 1, 6, 7, 8, 9, 10, 66, 84, 104, 126, 150, 1056, 1428, 1872, 2394, 3000, 22176, 31416, 43056, 57456, 75000, 576576, 848232, 1205568, 1666224, 2250000, 17873856, 27143424, 39783744, 56651616, 78750000, 643458816, 1004306688, 1511782272
Offset: 0

Views

Author

Labos Elemer, Apr 01 2003

Keywords

Comments

Quintic factorial sequences are generated by single 5-order recursion and appear in unified form.

Examples

			A008548, A034323, A034300, A034301, A034325 sequences are combed together as A081408(5n+r) with r=0,1,2,3,4.
		

Crossrefs

Cf. A001147, A002866, A034001, A007599, A034000, A007696, A000407, A034176, A034177, A008548, A034323, A034300, A034301, A034325 [double, triple, quartic, quintic, factorial subsequences], generated together in A081405-A081408.

Programs

  • GAP
    a:=[1,1,1,1,1];; for n in [6..40] do a[n]:=n*a[n-5]; od; a; # G. C. Greubel, Aug 15 2019
  • Haskell
    a081407 n = a081408_list !! n
    a081407_list = 1 : 1 : 1 : 1 : zipWith (*) [5..] a081407_list
    -- Reinhard Zumkeller, Jan 05 2012
    
  • Magma
    [n le 5 select 1 else n*Self(n-5): n in [1..40]]; // G. C. Greubel, Aug 15 2019
    
  • Mathematica
    a[0]=a[1]=a[2]=a[3]=a[4]=1; a[x_]:= (x+1)*a[x-5]; Table[a[n], {n, 40}]
  • PARI
    m=30; v=concat([1,1,1,1,1], vector(m-5)); for(n=6, m, v[n]=n*v[n-5] ); v \\ G. C. Greubel, Aug 15 2019
    
  • Sage
    def a(n):
        if (n<5): return 1
        else: return (n+1)*a(n-5)
    [a(n) for n in (0..40)] # G. C. Greubel, Aug 15 2019
    
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