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 21-28 of 28 results.

A052684 Expansion of e.g.f. 1/(1-2*x^2-x^3).

Original entry on oeis.org

1, 0, 4, 6, 96, 480, 6480, 60480, 887040, 11975040, 203212800, 3512678400, 69455232000, 1444668825600, 32953394073600, 796373690112000, 20671716409344000, 567677135241216000, 16550136029306880000
Offset: 0

Views

Author

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

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 30); Coefficients(R!(Laplace( 1/(1-2*x^2-x^3) ))); // G. C. Greubel, Jun 03 2022
    
  • Maple
    spec := [S,{S=Sequence(Prod(Z,Union(Z,Z,Prod(Z,Z))))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
  • Mathematica
    With[{nn=20},CoefficientList[Series[1/(1-2x^2-x^3),{x,0,nn}], x] Range[ 0,nn]!] (* Harvey P. Dale, Apr 22 2012 *)
    Table[n!*(Fibonacci[n]+(-1)^n), {n,0,40}] (* G. C. Greubel, Jun 03 2022 *)
  • SageMath
    [factorial(n)*(fibonacci(n) +(-1)^n) for n in (0..40)] # G. C. Greubel, Jun 03 2022

Formula

E.g.f.: 1/(1 - 2*x^2 - x^3).
D-finite recurrence: a(0)=1, a(1)=0, a(2)=4, a(n) = 2*n*(n-1)*a(n-2) + n*(n-1)*(n-2)*a(n-3).
a(n) = (n!/5)*Sum_{alpha=RootOf(-1+2*Z^2+Z^3)} (-6 + 7*alpha + 8*alpha^2)*alpha^(-1-n).
a(n) = n!*A008346(n). - R. J. Mathar, Nov 27 2011

A124377 Riordan array (1/(1-x-x^2),x/(1+x)).

Original entry on oeis.org

1, 1, 1, 2, 0, 1, 3, 2, -1, 1, 5, 1, 3, -2, 1, 8, 4, -2, 5, -3, 1, 13, 4, 6, -7, 8, -4, 1, 21, 9, -2, 13, -15, 12, -5, 1, 34, 12, 11, -15, 28, -27, 17, -6, 1, 55, 22, 1, 26, -43, 55, -44, 23, -7, 1, 89, 33, 21
Offset: 0

Views

Author

Paul Barry, Oct 29 2006

Keywords

Comments

First column is F(n+1). Second column is A008346. Row sums are F(n+2). Diagonal sums are A094966(n+1). Product of A007318 and A124377 is the Riordan array ((1-x)/(1-3x+x^2),x), the sequence array for F(2n+1).

Examples

			Triangle begins
1,
1, 1,
2, 0, 1,
3, 2, -1, 1,
5, 1, 3, -2, 1,
8, 4, -2, 5, -3, 1,
13, 4, 6, -7, 8, -4, 1,
21, 9, -2, 13, -15, 12, -5, 1
		

Crossrefs

Formula

Number triangle T(n,k)=sum{j=0..n-k, C(j-k,n-k-j)}*[k<=n]
T(n,k)=T(n-1,k-1)+2*T(n-2,k)-T(n-2,k-1)+T(n-3,k)-T(n-3,k-1), T(0,0)=T(1,0)=T(1,1)=1, T(n,k)=0 if k<0 or if k>n. - Philippe Deléham, Jan 12 2014
T(n,0)=A000045(n+1), T(n,n)=1, T(n,k)=T(n-1,k-1)-T(n-1,k) for 0Philippe Deléham, Jan 12 2014

A208153 Convolution triangle based on A006053.

Original entry on oeis.org

1, 1, 1, 3, 2, 1, 4, 7, 3, 1, 9, 14, 12, 4, 1, 14, 35, 31, 18, 5, 1, 28, 70, 87, 56, 25, 6, 1, 47, 154, 207, 175, 90, 33, 7, 1, 89, 306, 504, 476, 310, 134, 42, 8, 1, 155, 633, 1137, 1274, 941, 504, 189, 52, 9, 1
Offset: 0

Views

Author

Philippe Deléham, Feb 24 2012

Keywords

Comments

Riordan array (1/(1-x-2*x^2+x^3), x/(1-x-2*x^2+x^3)).
Subtriangle of triangle given by (0, 1, 2, -5/2, 1/10, 2/5, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (1, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.
Diagonal sums are A125691(n).
Row sums are A001654(n+1).
Mirror image of triangle in A188107.

Examples

			Triangle begins:
  1
  1, 1
  3, 2, 1
  4, 7, 3, 1
  9, 14, 12, 4, 1
  14, 35, 31, 18, 5, 1
Triangle (0, 1, 2, -5/2, 1/10, 2/5, 0, 0,...) DELTA (1, 0, 0, 0,...) begins:
  1
  0, 1
  0, 1, 1
  0, 3, 2, 1
  0, 4, 7, 3, 1
  0, 9, 14, 12, 4, 1
  0, 14, 35, 31, 18, 5, 1
		

Crossrefs

Programs

  • Mathematica
    nmax=9; Flatten[CoefficientList[Series[CoefficientList[Series[1/(1 - x - 2*x^2 + x^3 - y*x), {x, 0, nmax}], x], {y, 0, nmax}], y]] (* Indranil Ghosh, Mar 10 2017 *)

Formula

T(n,k) = T(n-1,k-1) + T(n-1,k) + 2*T(n-2,k) - T(n-3,k).
G.f.: 1/(1-x-2*x^2+x^3-y*x).
Sum_{k>=0} T(n-2*k,k) = A001045(n+1).
Sum_{k=0..n} T(n,k)*x^k = (-1)^n*A008346(n), A006053(n+2), A001654(n+1) for x = -1, 0, 1 respectively.

A215038 Partial sums of A066259: a(n) = Sum_{k=0..n} F(k+1)^2*F(k), n>=0, with the Fibonacci numbers F=A000045.

Original entry on oeis.org

0, 1, 5, 23, 98, 418, 1770, 7503, 31779, 134629, 570284, 2415788, 10233404, 43349461, 183631161, 777874251, 3295127934, 13958386366, 59128672790, 250473078515, 1061020985255, 4494557022121, 19039249069560, 80651553307128
Offset: 0

Views

Author

Wolfdieter Lang, Aug 09 2012

Keywords

Comments

For a derivation of the explicit form of this sum see the link under A215308 on the partial summation formula, eq. (7).

Examples

			a(2) = 0 + 1^2*1 + 2^2*1 = 1 + 4 = 5.
		

Crossrefs

Formula

a(n) = Sum_{k=0..n} A066259(k) = Sum_{k=0..n} F(k+1)^2*F(k), n >= 0, with A066259(0)=0.
a(n) = (F(n+2)*F(n+1)^2 - (-1)^n*F(n) - 1)/2 = (A066258(n+1) - (-1)^n*A008346(n))/2, n >= 0.
O.g.f.: x*(1+x)/((1+x-x^2)*(1-4*x-x^2)*(1-x)) (from A066259).
E.g.f.: (2*exp(-x/2)*(5*cosh(sqrt(5)*x/2) + 3*sqrt(5)*sinh(sqrt(5)*x/2)) + exp(2*x)*(15*cosh(sqrt(15)*x) + 7*sqrt(5)*sinh(sqrt(5)*x)) - 25*exp(x))/50. - Stefano Spezia, Oct 28 2024

A230449 T(n, k) = T(n-1, k-1) + T(n-1, k) with T(n, 0) = 1 and T(n, n) = A052952(n), n >= 0 and 0 <= k <= n.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 1, 3, 5, 4, 1, 4, 8, 9, 8, 1, 5, 12, 17, 17, 12, 1, 6, 17, 29, 34, 29, 21, 1, 7, 23, 46, 63, 63, 50, 33, 1, 8, 30, 69, 109, 126, 113, 83, 55, 1, 9, 38, 99, 178, 235, 239, 196, 138, 88, 1, 10, 47, 137, 277, 413, 474, 435, 334, 226, 144
Offset: 0

Views

Author

Johannes W. Meijer, Oct 19 2013

Keywords

Comments

The right hand columns of triangle T(n, k) represent the Kn2p sums of the ‘Races with Ties’ triangle A035317. See A180662 for the definitions of these sums.
The row sums lead to A094687, the convolution of Fibonacci and Jacobsthal numbers, and the alternating row sums lead to A008346.
The backwards antidiagonal sums equal Kn21(n) = (-1)^n*A175722(n).

Examples

			The first few rows of triangle T(n, k), n >= 0 and 0 <= k <= n.
n/k 0   1   2    3    4     5     6     7
------------------------------------------------
0|  1
1|  1,  1
2|  1,  2,  3
3|  1,  3,  5,   4
4|  1,  4,  8,   9,   8
5|  1,  5, 12,  17,  17,   12
6|  1,  6, 17,  29,  34,   29,   21
7|  1,  7, 23,  46,  63,   63,   50,   33
The triangle as a square array Tsq(n, k) = T(n+k, k), n >= 0 and k >= 0.
n/k 0   1   2    3    4     5     6     7
------------------------------------------------
0|  1,  1,  3,   4,   8,   12,   21,   33
1|  1,  2,  5,   9,  17,   29,   50,   83
2|  1,  3,  8,  17,  34,   63,  113,  196
3|  1,  4, 12,  29,  63,  126,  239,  435
4|  1,  5, 17,  46, 109,  235,  474,  909
5|  1,  6, 23,  69, 178,  413,  887, 1796
6|  1,  7, 30,  99, 277,  690, 1577, 3373
7|  1,  8, 38, 137, 414, 1104, 2681, 6054
		

Crossrefs

Cf. (Triangle columns) A000012, A000027, A089071, A052952, A129696

Programs

  • Maple
    T:= proc(n, k) option remember: if k=0 then return(1) elif k=n then return(combinat[fibonacci](n+2) - (1-(-1)^n)/2) else procname(n-1,k-1)+procname(n-1,k) fi: end: seq(seq(T(n, k), k=0..n), n=0..10); # End first program.
    T := proc(n, k): add(A035317(k-p+n-k, k-2*p), p=0..floor(k/2)) end: A035317 := proc(n, k): add((-1)^(i+k) * binomial(i+n-k+1, i), i=0..k) end: seq(seq(T(n, k), k=0..n), n=0..10); # End second program.

Formula

T(n, k) = T(n-1, k-1) + T(n-1, k) with T(n, 0) = 1 and T(n, n) = F(n+2) - (1-(-1)^n)/2 = A052952(n), with F(n) = A000045(n), the Fibonacci numbers, n >= 0 and 0 <= k <= n.
T(n+p-1, n) = sum(A035317(n-k+p-1, n-2*k), k=0..floor(n/2)), n >= 0 and p >= 1.
The triangle as a square array Tsq(n, k) = T(n+k, k), n >= 0 and k >= 0.
Tsq(n, k) = sum(Tsq(n-1, i), i=0..k), n >= 1 and k >= 0, with Tsq(0, k) = A052952(k).
Tsq(n, k) = sum(A035317(n+k-i, k-2*i), i=0..floor(k/2)), n >= 0 and k >= 0.
Tsq(n, k) = A052952(2*n+k) - sum(A035317(n+k+i+1, k+2*i+2), i = 0..n-1)
The G.f. generates the terms in the n-th row of the square array Tsq(n, k).
G.f.: (-1)^(n)/((-1+x+x^2)*(x+1)*(x-1)^(n+1)), n >= 0.

A320508 T(n,k) = binomial(n - k - 1, k), 0 <= k < n, and T(n,n) = (-1)^n, triangle read by rows.

Original entry on oeis.org

1, 1, -1, 1, 0, 1, 1, 1, 0, -1, 1, 2, 0, 0, 1, 1, 3, 1, 0, 0, -1, 1, 4, 3, 0, 0, 0, 1, 1, 5, 6, 1, 0, 0, 0, -1, 1, 6, 10, 4, 0, 0, 0, 0, 1, 1, 7, 15, 10, 1, 0, 0, 0, 0, -1, 1, 8, 21, 20, 5, 0, 0, 0, 0, 0, 1, 1, 9, 28, 35, 15, 1, 0, 0, 0, 0, 0, -1, 1, 10, 36
Offset: 0

Views

Author

Keywords

Comments

Differs from A164925 in signs.
The n-th row consists of the coefficients in the expansion of (-x)^n + (((1 + sqrt(1 + 4*x))/2)^n -((1 - sqrt(1 + 4*x))/2)^n )/sqrt(1 + 4*x).
The coefficients in the expansion of Sum_{j=0..floor((n - 1)/2)} T(n,k)*x^(n - 2*j - 1) yield the n-th row in A168561, the coefficients of the n-th Fibonacci polynomial.
Row n sums up to Fibonacci(n) + (-1)^n (A008346).

Examples

			Triangle begins:
    1;
    1, -1;
    1,  0,  1;
    1,  1,  0, -1;
    1,  2,  0,  0,  1;
    1,  3,  1,  0,  0, -1;
    1,  4,  3,  0,  0,  0, 1;
    1,  5,  6,  1,  0,  0, 0, -1;
    1,  6, 10,  4,  0,  0, 0,  0, 1;
    1,  7, 15, 10,  1,  0, 0,  0, 0, -1;
    1,  8, 21, 20,  5,  0, 0,  0, 0,  0, 1;
    1,  9, 28, 35, 15,  1, 0,  0, 0,  0, 0, -1;
    ...
		

Crossrefs

Programs

  • Mathematica
    Table[Table[Binomial[n - k - 1, k], {k, 0, n}], {n, 0, 12}]//Flatten
  • Maxima
    create_list(binomial(n - k - 1, k), n, 0, 12, k, 0, n);

Formula

G.f.: 1/((1 + x*y)*(1 - y - x*y^2)).
E.g.f.: exp(-x*y) + (exp(y*(1 + sqrt(1 + 4*x))/2) - exp(y*(1 - sqrt(1 + 4*x))/2))/sqrt(1 + 4*x).
T(n,1) = A023443(n).

A099096 Riordan array (1,2-x).

Original entry on oeis.org

1, 0, 2, 0, -1, 4, 0, 0, -4, 8, 0, 0, 1, -12, 16, 0, 0, 0, 6, -32, 32, 0, 0, 0, -1, 24, -80, 64, 0, 0, 0, 0, -8, 80, -192, 128, 0, 0, 0, 0, 1, -40, 240, -448, 256, 0, 0, 0, 0, 0, 10, -160, 672, -1024, 512, 0, 0, 0, 0, 0, -1, 60, -560, 1792, -2304, 1024, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Paul Barry, Sep 25 2004

Keywords

Comments

Row sums are n+1 = Sum_{k=0..n} binomial(k,n-k)*2^(2k-n)*(-1)^(n-k). Diagonal sums are (-1)^n*A008346(n). The Riordan array (1,s+tx) defines T(n,k) = binomial(k,n-k)*s^k*(t/s)^(n-k). The row sums satisfy a(n) = s*a(n-1) + t*a(n-2) and the diagonal sums satisfy a(n) = s*a(n-2) + t*a(n-3).
Triangle T(n,k), 0 <= k <= n, read by rows given by [0, -1/2, 1/2, 0, 0, 0, 0, ...] DELTA [2, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938. - Philippe Deléham, Nov 10 2008

Examples

			Rows begin
  1;
  0,   2;
  0,  -1,   4;
  0,   0,  -4,   8;
  0,   0,   1, -12,  16;
  ...
		

Crossrefs

Cf. A099089.

Programs

  • PARI
    /* Matrix power T^m formula: [T^m](n,k) = */ {T(n,k,m=1)=polcoeff((1 - (1-x +x*O(x^n))^(2^m) )^k,n)} \\ Paul D. Hanna, Nov 15 2007

Formula

Number triangle T(n, k) = binomial(k, n-k)*2^k*(-1/2)^(n-k); columns have g.f. (2x-x^2)^k.
G.f. of column k of matrix power T^m = (1 - (1-x)^(2^m))^k for k >= 0, when including the leading zeros that appear above the diagonal. - Paul D. Hanna, Nov 15 2007
T(n,k) = 2*T(n-1,k-1) - T(n-2,k-1), with T(0,0)=1, T(n,k)=0 if k < 0 or if k > n. - Philippe Deléham, Nov 25 2013
G.f.: 1/(1-2*x*y+x^2*y). - R. J. Mathar, Aug 12 2015

A099494 A Chebyshev transform of Fibonacci(n)+(-1)^n.

Original entry on oeis.org

1, 0, 1, 1, -1, 0, 0, -2, 0, 1, -1, 1, 2, -1, 0, 1, -2, -1, 1, -1, 0, 2, 0, 0, 1, -1, -1, 0, -1, 0, 1, 0, 1, 1, -1, 0, 0, -2, 0, 1, -1, 1, 2, -1, 0, 1, -2, -1, 1, -1, 0, 2, 0, 0, 1, -1, -1, 0, -1, 0, 1, 0, 1, 1, -1, 0, 0, -2, 0, 1, -1, 1, 2, -1, 0, 1, -2, -1, 1, -1, 0, 2, 0, 0, 1, -1, -1
Offset: 0

Views

Author

Paul Barry, Oct 19 2004

Keywords

Comments

A Chebyshev transform of A008346, which has g.f. 1/(1-2x^2-x^3). The image of G(x) under the Chebyshev transform is (1/(1+x^2))*G(x/(1+x^2)).
Periodic with period length 30. - Ray Chandler, Sep 08 2015

Crossrefs

Formula

G.f.: (1+x^2)^2/(1+x^2-x^3+x^4+x^6).
a(n) = -a(n-2)+a(n-3)-a(n-4)-a(n-6).
a(n) = Sum_{k=0..floor(n/2)} binomial(n-k, k)*(-1)^k*(F(n-2*k)+(-1)^(n-2*k)).
a(n) = A014019(n-1) + A000484(n).
Previous Showing 21-28 of 28 results.