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.

A129184 Shift operator, right.

Original entry on oeis.org

0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0
Offset: 1

Views

Author

Gary W. Adamson, Apr 01 2007

Keywords

Comments

Let A129184 = matrix M, then M*V, (V a vector); shifts V to the right, preceded by zeros. Example: M*V, V = [1, 2, 3, ...] = [0, 1, 2, 3, ...]. A129185 = left shift operator.
Given a polynomial sequence p_n(x) with p_0(x)=1 and the lowering and raising operators L and R defined by L P_n(x)= n * P_(n-1)(x) and R P_n(x)= P_(n+1)(x), the matrix T represents the action of R in the p_n(x) basis. For p_n(x) = x^n, L = D = d/dx and R = x. For p_n(x)= x^n/n!, L= DxD and R=D^(-1). - Tom Copeland, Nov 10 2012

Examples

			First few rows of the triangle:
  0;
  1, 0;
  0, 1, 0;
  0, 0, 1, 0;
  0, 0, 0, 1, 0;
  ...
		

Crossrefs

Formula

Infinite lower triangular matrix with all 1's in the subdiagonal and the rest zeros.
From Tom Copeland, Nov 10 2012: (Start)
Let M(t) = I/(I-t*T) = I + t*T + (t*T)^2 + ... where T is the shift operator matrix and I the Identity matrix. Then the inverse matrix is MI(t)=(I-tT) and M(t) is A000012 with each n-th diagonal multiplied by t^n. M(1)=A000012 with inverse MI(1)=A167374. Row sums of M(2), M(3), and M(4) are A000225, A003462, and A002450.
Let E(t)=exp(t*T) with inverse E(-t). Then E(t) is A000012 with each n-th diagonal multiplied by t^n/n! and each row represents e^t truncated at the n+1 term.
The matrix operation b = T*a can be characterized in several ways in terms of the coefficients a(n) and b(n), their o.g.f.s A(x) and B(x), or e.g.f.s EA(x) and EB(x):
1) b(0) = 0, b(n) = a(n-1),
2) B(x) = x A(x), or
3) EB(x) = D^(-1) EA(x), where D^(-1)x^j/j! = x^(j+1)/(j+1)!.
The operator M(t) can be characterized as
4)M(t)EA(x)= sum(n>=0)a(n)[e^(x*t)-[1+x*t+...+ (x*t)^(n-1)/(n-1)!]]/t^n
= exp(a*D_y)[t*e^(x*t)-y*e(x*y)]/(t-y)
= [t*e^(x*t)-a*e(x*a)]/(t-a), umbrally where (a)^k=a_k,
5)[M(t) * a]_n = a(0)t^n +a(1)t^(n-1)+a(2)t^(n-2)+...+a(n).
The exponentiated operator can be characterized as
6) E(t) A(x) = exp(t*x) A(x),
7) E(t) EA(x) = exp(t*D^(-1)) EA(x)
8) [E(t) * a]_n = a(0)t^n/n! + a(1)t^(n-1)/(n-1)! + ... + a(n).
(End)
a(n) = A010054(n+1). - Andrew Howroyd, Feb 02 2020

Extensions

Terms a(46) and beyond from Andrew Howroyd, Feb 02 2020

A115717 A divide-and-conquer triangle related to A007583.

Original entry on oeis.org

1, 0, 1, 3, -1, 1, 0, 0, 0, 1, 0, 4, -1, -1, 1, 0, 0, 0, 0, 0, 1, 12, -4, 4, 0, -1, -1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 4, 0, 0, -1, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 16, -4, -4, 4, 0, 0, 0, -1, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, -1, -1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 48, -16, 16, 0, -4, -4, 4, 0, 0, 0, 0, 0, -1, -1, 1
Offset: 0

Views

Author

Paul Barry, Jan 29 2006

Keywords

Comments

Product of (1-x, x), which is A167374, and number triangle A115715.

Examples

			Triangle begins
   1;
   0,   1;
   3,  -1,  1;
   0,   0,  0,  1;
   0,   4, -1, -1,  1;
   0,   0,  0,  0,  0,  1;
  12,  -4,  4,  0, -1, -1,  1;
   0,   0,  0,  0,  0,  0,  0,  1;
   0,   0,  0,  4,  0,  0, -1, -1,  1;
   0,   0,  0,  0,  0,  0,  0,  0,  0,  1;
   0,  16, -4, -4,  4,  0,  0,  0, -1, -1,  1;
   0,   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1;
   0,   0,  0,  0,  0,  4,  0,  0,  0,  0, -1, -1,  1;
   0,   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1;
  48, -16, 16,  0, -4, -4,  4,  0,  0,  0,  0,  0, -1, -1,  1;
		

Crossrefs

Cf. A007583, A115715, A115716 (row sums), A167374.

Programs

  • Maple
    A115717 := proc(n,k)
        add( A167374(n,j)*A115715(j,k),j=k..n) ;
    end proc: # R. J. Mathar, Sep 07 2016
  • Mathematica
    A167374[n_, k_]:= If[k>n-2, (-1)^(n-k), 0];
    g[n_, k_]:= g[n, k]= If[k==n, 1, If[k==n-1, -Mod[n, 2], If[n==2*k+2, -4, 0]]]; (* g = A115713 *)
    f[n_, k_]:= f[n, k]= If[k==n, 1, -Sum[f[n,j]*g[j,k], {j,k+1,n}]]; (* f=A115715 *)
    A115717[n_, k_]:= A115717[n, k]= Sum[A167374[n,j]*f[j,k], {j,k,n}];
    Table[A115717[n, k], {n,0,15}, {k,0,n}]//Flatten (* G. C. Greubel, Nov 23 2021 *)
  • Sage
    @cached_function
    def A115717(n,k):
        def A167374(n, k):
            if (k>n-2): return (-1)^(n-k)
            else: return 0
        def A115713(n,k):
            if (k==n): return 1
            elif (k==n-1): return -(n%2)
            elif (n==2*k+2): return -4
            else: return 0
        def A115715(n,k):
            if (k==0): return 4^(floor(log(n+2, 2)) -1)
            elif (k==n): return 1
            elif (k==n-1): return (n%2)
            else: return (-1)*sum( A115715(n,j+k+1)*A115713(j+k+1,k) for j in (0..n-k-1) )
        return sum( A167374(n, j+k)*A115715(j+k, k) for j in (0..n-k) )
    flatten([[A115717(n,k) for k in (0..n)] for n in (0..15)]) # G. C. Greubel, Nov 23 2021

Formula

Sum_{k=0..n} T(n, k) = A115716(n).
T(n ,k) = Sum_{j=k..n} A167374(n, j)*A115715(j, k). - R. J. Mathar, Sep 07 2016

A318259 Generalized Worpitzky numbers W_{m}(n,k) for m = 2, n >= 0 and 0 <= k <= n, triangle read by rows.

Original entry on oeis.org

1, -1, 1, 5, -11, 6, -61, 211, -240, 90, 1385, -6551, 11466, -8820, 2520, -50521, 303271, -719580, 844830, -491400, 113400, 2702765, -19665491, 58998126, -93511440, 82661040, -38669400, 7484400, -199360981, 1704396331, -6187282920, 12372329970, -14727913200, 10443232800, -4086482400, 681080400
Offset: 0

Views

Author

Peter Luschny, Sep 06 2018

Keywords

Comments

The triangle can be seen as a member of a family of generalized Worpitzky numbers A028246. See the cross-references for some other members.
The unsigned numbers have row sums A210657 which points to an interpretation of the unsigned numbers as a refinement of marked Schröder paths (see Josuat-Vergès and Kim).

Examples

			[0] [      1]
[1] [     -1,         1]
[2] [      5,       -11,        6]
[3] [    -61,       211,     -240,        90]
[4] [   1385,     -6551,    11466,     -8820,     2520]
[5] [ -50521,    303271,  -719580,    844830,  -491400,    113400]
[6] [2702765, -19665491, 58998126, -93511440, 82661040, -38669400, 7484400]
		

Crossrefs

Row sums are A000007, alternating row sums are A210657.
Cf. T(n,n) = A000680, T(n, 0) = A028296(n) (Gudermannian), A000364 (Euler secant), A241171 (Joffe's differences), A028246 (Worpitzky).
Cf. A167374 (m=0), A028246 & A163626 (m=1), this seq (m=2), A318260 (m=3).

Programs

  • Maple
    Joffe := proc(n, k) option remember; if k > n then 0 elif k = 0 then k^n else
    k*(2*k-1)*Joffe(n-1, k-1)+k^2*Joffe(n-1, k) fi end:
    T := (n, k) -> add((-1)^(k-j)*binomial(n-j, n-k)*add((-1)^i*Joffe(n,i)*
    binomial(n-i, j), i=0..n), j=0..k):
    seq(seq(T(n, k), k=0..n), n=0..6);
  • Mathematica
    Joffe[0, 0] = 1; Joffe[n_, k_] := Joffe[n, k] = If[k>n, 0, If[k == 0,k^n, k*(2*k-1)*Joffe[n-1, k-1] + k^2*Joffe[n-1, k]]];
    T[n_, k_] := Sum[(-1)^(k-j)*Binomial[n-j, n-k]*Sum[(-1)^i*Joffe[n, i]* Binomial[n-i, j], {i, 0, n}], {j, 0, k}];
    Table[T[n, k], {n, 0, 7}, {k, 0, n}] // Flatten (* Jean-François Alcover, Feb 18 2019, from Maple *)
  • Sage
    def EW(m, n):
        @cached_function
        def S(m, n):
            R. = ZZ[]
            if n == 0: return R(1)
            return R(sum(binomial(m*n, m*k)*S(m, n-k)*x for k in (1..n)))
        s = S(m, n).list()
        c = lambda k: sum((-1)^(k-j)*binomial(n-j,n-k)*
            sum((-1)^i*s[i]*binomial(n-i,j) for i in (0..n)) for j in (0..k))
        return [c(k) for k in (0..n)]
    def A318259row(n): return EW(2, n)
    flatten([A318259row(n) for n in (0..6)])

Formula

Let S(n, k) denote Joffe's central differences of zero (A241171) extended to the case n = 0 and k = 0 by prepending a column 1, 0, 0, 0,... to the triangle, then:
T(n,k) = Sum_{j=0..k}((-1)^(k-j)*C(n-j,n-k)*Sum_{i=0..n}((-1)^i*S(n,i)*C(n-i,j))).

A318260 Generalized Worpitzky numbers W_{m}(n,k) for m = 3, n >= 0 and 0 <= k <= n, triangle read by rows.

Original entry on oeis.org

1, -1, 1, 19, -39, 20, -1513, 4705, -4872, 1680, 315523, -1314807, 2052644, -1422960, 369600, -136085041, 710968441, -1484552160, 1548707160, -807206400, 168168000, 105261234643, -661231439271, 1729495989332, -2410936679424, 1889230062720, -789044256000, 137225088000
Offset: 0

Views

Author

Peter Luschny, Sep 06 2018

Keywords

Comments

The triangle can be seen as a member of a family of generalized Worpitzky numbers A028246. See A318259 and the cross-references for some other members.

Examples

			[0] [         1]
[1] [        -1,         1]
[2] [        19,       -39,          20]
[3] [     -1513,      4705,       -4872,       1680]
[4] [    315523,  -1314807,     2052644,   -1422960,     369600]
[5] [-136085041, 710968441, -1484552160, 1548707160, -807206400, 168168000]
		

Crossrefs

Cf. T(n,0) ~ A002115(n) (signed), T(n,n) = A014606.
Cf. A167374 (m=0), A028246 & A163626 (m=1), A318259 (m=2), this seq (m=3).

Programs

  • Sage
    # uses[EW from A318259]
    def A318260row(n): return EW(3, n)
    print(flatten([A318260row(n) for n in (0..6)]))

Formula

Let P(m,n) = Sum_{k=1..n} binomial(m*n, m*k)*P(m, n-k)*x with P(m,0) = 1
and S(n,k) = [x^k]P(3,n), then T(n,k) = Sum_{j=0..k}((-1)^(k-j)*binomial(n-j, n-k)* Sum_{i=0..n}((-1)^i*S(n,i)*binomial(n-i,j))).

A338291 Matrix inverse of the rascal triangle (A077028), read across rows.

Original entry on oeis.org

1, -1, 1, 1, -2, 1, -1, 3, -3, 1, 2, -6, 7, -4, 1, -6, 18, -21, 13, -5, 1, 24, -72, 84, -52, 21, -6, 1, -120, 360, -420, 260, -105, 31, -7, 1, 720, -2160, 2520, -1560, 630, -186, 43, -8, 1, -5040, 15120, -17640, 10920, -4410, 1302, -301, 57, -9, 1
Offset: 0

Views

Author

Werner Schulte, Oct 20 2020

Keywords

Comments

The columns of this triangle are related to factorial numbers (A000142).
There is a family of triangles T(m;n,k) = 1 + m*k*(n-k) for some fixed integer m (for m >= 0 see A296180, Comments) and 0 <= k <= n. They satisfy the equation T(-m;n,k) = 2 - T(m;n,k). The corresponding matrices inverse M = T^(-1) are given by: M(m;n,n) = 1 for n >= 0, and M(m;n,n-1) = m*(1-n) - 1 for n > 0, and M(m;n,k) = (-1)^(n-k) * m * (m * k*(k+1) + 1) * Product_{i=k+1..n-2} (m*(i+1) - 1) for 0 <= k <= n-2. For special cases of the M(m;n,k) see A338817 (m=-1), and A167374 (m=0), and this triangle (m=1).

Examples

			The triangle T(n,k) for 0 <= k <= n starts:
n\k :      0      1       2      3      4     5     6   7   8  9
================================================================
  0 :      1
  1 :     -1      1
  2 :      1     -2       1
  3 :     -1      3      -3      1
  4 :      2     -6       7     -4      1
  5 :     -6     18     -21     13     -5     1
  6 :     24    -72      84    -52     21    -6     1
  7 :   -120    360    -420    260   -105    31    -7   1
  8 :    720  -2160    2520  -1560    630  -186    43  -8   1
  9 :  -5040  15120  -17640  10920  -4410  1302  -301  57  -9  1
etc.
		

Crossrefs

Programs

  • PARI
    for(n=0,10,for(k=0,n,if(k==n,print(" 1"),if(k==n-1,print1(-n,", "),print1((-1)^(n-k)*(k^2+k+1)*(n-2)!/k!,", ")))))
    
  • PARI
    1/matrix(10, 10, n, k, n--; k--; if (n>=k, k*(n-k) + 1)) \\ Michel Marcus, Nov 11 2020

Formula

T(n,n) = 1 for n >= 0, and T(n,n-1) = -n for n > 0, and T(n,n-2) = n^2 - 3*n + 3 for n > 1, and T(n,k) = (-1)^(n-k) * (k^2 + k + 1) * (n-2)! / k! for 0 <= k <= n-2.
T(n,k) = (2-n) * T(n-1,k) for 0 <= k < n-2.
T(n,k) = T(k+2,k) * (-1)^(n-k) * (n-2)! / k! for 0 <= k <= n-2.
Row sums are A000007(n) for n >= 0.

A167371 Triangle, read by rows, given by [0,1,-1,0,0,0,0,0,0,0,0,...] DELTA [1,0,-1,1,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1
Offset: 0

Views

Author

Philippe Deléham, Nov 02 2009

Keywords

Comments

Diagonal sums: A060576.
A167374*A154325 formatted as lower triangular matrix. - Philippe Deléham, Nov 19 2009

Examples

			Triangle begins:
  1;
  0, 1;
  0, 1, 1;
  0, 0, 1, 1;
  0, 0, 0, 1, 1;
  0, 0, 0, 0, 1, 1; ...
		

Crossrefs

Formula

Sum_{k=0..n} T(n,k)*x^k = A000007(n), A046698(n+1), A111286(n+1), A027327(n) for x= 0, 1, 2, 3 respectively.
G.f.: (1+x^2*y)/(1-x*y). - Philippe Deléham, Nov 09 2013
T(n,k) = T(n-1,k-1) for n > 2, T(0,0) = T(1,1) = T(2,1) = T(2,2) = 1, T(1,0) = T(2,0) = 0, T(n,k) = 0 if k < 0 or if k > n. - Philippe Deléham, Nov 09 2013
Previous Showing 11-16 of 16 results.