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 1-4 of 4 results.

A094408 a(n) = Sum_{k = 0..n} 3^k*A085707(n,k).

Original entry on oeis.org

1, 1, 4, 37, 631, 17266, 692785, 38325925, 2795925136, 260056965205, 30038178784699, 4218296308789630, 707778995370264001, 139840360858571766121
Offset: 0

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Author

Philippe Deléham, Jun 04 2004

Keywords

Comments

Sum_{k = 0..n} x^k*A085707(n,k) give A006846(n), A005647(n), A000364(n) for x = 1, 2, 4 respectively.

Crossrefs

Cf. A085707.

A259908 Triangle read by rows: Hammersley's numbers c_{j,k} arising from a formula for A085707(n,k).

Original entry on oeis.org

1, 3, 5, 17, 70, 61, 155, 1143, 2317, 1385, 2073, 23716, 82286, 110556, 50521, 38227, 623753, 3243270, 7258090, 7293671, 2702765, 929569, 20454498, 147624355, 484343420, 796220487, 639139202, 199360981
Offset: 1

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Author

N. J. A. Sloane, Jul 07 2015

Keywords

Examples

			Triangle begins:
       1,
       3,        5,
      17,       70,        61,
     155,     1143,      2317,      1385,
    2073,    23716,     82286,    110556,     50521,
   38227,   623753,   3243270,   7258090,   7293671,   2702765,
  929569, 20454498, 147624355, 484343420, 796220487, 639139202, 199360981,
  ...
		

Crossrefs

Cf. A085707.
Diagonals are A001469, A000364.

Extensions

Missing row 5 added by Michel Marcus, Feb 07 2023

A065547 Triangle of Salie numbers.

Original entry on oeis.org

1, 0, 1, 0, -1, 1, 0, 3, -3, 1, 0, -17, 17, -6, 1, 0, 155, -155, 55, -10, 1, 0, -2073, 2073, -736, 135, -15, 1, 0, 38227, -38227, 13573, -2492, 280, -21, 1, 0, -929569, 929569, -330058, 60605, -6818, 518, -28, 1, 0, 28820619, -28820619, 10233219, -1879038, 211419, -16086, 882, -36, 1, 0, -1109652905
Offset: 0

Views

Author

Wouter Meeussen, Dec 02 2001

Keywords

Comments

Coefficients of polynomials H(n,x) related to Euler polynomials through H(n,x(x-1)) = E(2n,x).

Examples

			Triangle begins:
 1;
 0,   1;
 0,  -1,    1;
 0,   3,   -3,  1;
 0, -17,   17, -6,   1;
 0, 155, -155, 55, -10, 1;
 ...
		

Crossrefs

Sum_{k>=0} (-1)^(n+k)*2^(n-k)*T(n, k) = A005647(n). Sum_{k>=0} (-1)^(n+k)*2^(2n-k)*T(n, k) = A000795(n). Sum_{k>=0} (-1)^(n+k)*T(n, k) = A006846(n), where A006846 = Hammersley's polynomial p_n(1). - Philippe Deléham, Feb 26 2004.
Column sequences (without leading zeros) give, for k=1..10: A065547 (twice), A095652-9.
See A085707 for unsigned and transposed version.
See A098435 for negative values of n, k.

Programs

  • Mathematica
    h[n_, x_] := Sum[c[k]*x^k, {k, 0, n}]; eq[n_] := SolveAlways[h[n, x*(x - 1)] == EulerE[2*n, x], x]; row[n_] := Table[c[k], {k, 0, n}] /. eq[n] // First; Table[row[n], {n, 0, 10}] // Flatten (* Jean-François Alcover, Oct 02 2013 *)
  • PARI
    { S2(n, k) = (1/k!)*sum(i=0,k,(-1)^(k-i)*binomial(k,i)*i^n) }{ Eu(n) = sum(m=0,n,(-1)^m*m!*S2(n+1,m+1)*(-1)^floor(m/4)*2^-floor(m/2)*((m+1)%4!=0)) } T(n,k)=if(nRalf Stephan

Formula

E.g.f.: Sum_{n, k=0..oo} T(n, k) t^k x^(2n)/(2n)! = cosh(sqrt(1+4t) x/2) / cosh(x/2).
T(k, n) = Sum_{i=0..n-k} A028296(i)/4^(n-k)*C(2n, 2i)*C(n-i, n-k-i), or 0 if n
Polynomial recurrences: x^n = Sum_{0<=2i<=n} C(n, 2i)*H(n-i, x); (1/4+x)^n = Sum_{m=0..n} C(2n, 2m)*(1/4)^(n-m)*H(m, x).
Dumont/Zeng give a continued fraction and other formulas.
Triangle T(n, k) read by rows; given by [0, -1, -2, -4, -6, -9, -12, -16, ...] DELTA A000035, where DELTA is Deléham's operator defined in A084938.
Sum_{k=0..n} (-4)^(n-k)*T(n,k) = A000364(n) (Euler numbers). - Philippe Deléham, Oct 25 2006

Extensions

Edited by Ralf Stephan, Sep 08 2004

A006846 Hammersley's polynomial p_n(1).

Original entry on oeis.org

1, 1, 2, 7, 41, 376, 5033, 92821, 2257166, 69981919, 2694447797, 126128146156, 7054258103921, 464584757637001, 35586641825705882, 3136942184333040727, 315295985573234822561, 35843594275585750890976, 4575961401477587844760793, 651880406652100451820206941
Offset: 0

Keywords

Comments

Equals column 0 of triangle A104027. Also equals column 0 of triangle A104030 (offset 1). Both A104027 and A104030 involve the trinomial coefficients. - Paul D. Hanna, Mar 06 2005

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Julia
    function A006846list(len::Int)  # Algorithm of L. Seidel (1877)
        R = Array{BigInt}(len)
        A = fill(BigInt(0), len+1); A[1] = 1
        for n in 1:len
            for k in n:-1:2 A[k] += A[k+1] end
            for k in 2:1:n A[k] += A[k-1] end
            R[n] = A[n]
        end
        return R
    end
    println(A006846list(20)) # Peter Luschny, Jan 02 2018
  • Maple
    A006846 := proc(n)
        option remember ;
        if n =0 then
            return 1;
        else
            add(binomial(2*n,2*m)*procname(m)/(-4)^(n-m),m=0..n-1) ;
            (3/4)^n-% ;
        end if
    end proc:
    seq(A006846(n),n=0..20) ; # R. J. Mathar, Jan 10 2018
  • Mathematica
    h[n_, x_] := Sum[c[k] x^k, {k, 0, n}]; eq[n_] := SolveAlways[h[n, x*(x-1)] == EulerE[2*n, x], x]; a[n_] := Sum[(-1)^(n+k)*c[k], {k, 0, n}] /. eq[n] // First; Table[a[n], {n, 0, 15}]   (* Jean-François Alcover, Oct 02 2013, after Philippe Deléham *)
  • PARI
    {a(n)=local(X=x+x*O(x^(2*n))); round((2*n)!*polcoeff(cosh(sqrt(3)*X/2)/cos(X/2),2*n))} \\ Paul D. Hanna
    

Formula

a(n) = Sum_{k>=0} (-1)^(n+k)*A065547(n, k) = Sum_{k>=0} A085707(n, k). - Philippe Deléham, Feb 26 2004
E.g.f.: cosh(sqrt(3)*x/2)/cos(x/2) = Sum_{n>=0} a(n)*x^(2n)/(2n)!. - Paul D. Hanna, Feb 27 2005
a(n) = (-1)^n*A104027(n, 0). a(n+1) = (-1)^(n+1)*A104030(n, 0). - Paul D. Hanna, Mar 06 2005
G.f.: 1/(1-x/(1-x/(1-3x/(1-4x/(1-7x/(1-.../(1-ceiling((n+1)^2/4)*x/(1-... (continued fraction). - Paul Barry, Feb 24 2010
a(n) ~ 4*cosh(sqrt(3)*Pi/2) * (2*n)! / Pi^(2*n+1). - Vaclav Kotesovec, Jun 07 2021
Showing 1-4 of 4 results.