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 1-5 of 5 results.

A107056 Matrix inverse of A103247, so that T(n,k) = C(n,k)*A010842(n-k), read by rows.

Original entry on oeis.org

1, 3, 1, 10, 6, 1, 38, 30, 9, 1, 168, 152, 60, 12, 1, 872, 840, 380, 100, 15, 1, 5296, 5232, 2520, 760, 150, 18, 1, 37200, 37072, 18312, 5880, 1330, 210, 21, 1, 297856, 297600, 148288, 48832, 11760, 2128, 280, 24, 1, 2681216, 2680704, 1339200, 444864, 109872
Offset: 0

Views

Author

Paul D. Hanna, May 19 2005

Keywords

Comments

A103247(n,k) is the coefficient of x^k in the monic characteristic polynomial of the n X n matrix with 3's on the diagonal and 1's elsewhere.

Examples

			Triangle T begins:
1;
3,1;
10,6,1;
38,30,9,1;
168,152,60,12,1;
872,840,380,100,15,1;
5296,5232,2520,760,150,18,1; ...
where T(n,k) = A010842(n-k)*binomial(n,k).
Matrix logarithm L begins:
0;
-3,0;
-1,-6,0;
-2,-3,-9,0;
-6,-8,-6,-12,0;
-24,-30,-20,-10,-15,0; ...
where L(n,k) = L(n,0)*binomial(n,k),
with L(n,0)=-(n-1)! for n>1, L(1,0)=-3, L(0,0)=0.
		

Crossrefs

Programs

  • PARI
    T(n,k)=n!/k!*sum(j=0,n-k,2^(n-k-j)/(n-k-j)!)

Formula

T(n, k) = n!/k!*Sum_{j=0..n-k} 2^(n-k-j)/(n-k-j)!.

A103236 Triangular matrix T, read by rows, that satisfies: T^2 + 2*T = SHIFTUP(T), also T^(n+1) + 2*T^n = SHIFTUP(T^n - D*T^(n-1)) for all n, where D is a diagonal matrix with diagonal(D) = diagonal(T) = {1,2,3,...}.

Original entry on oeis.org

1, 3, 2, 15, 8, 3, 114, 56, 15, 4, 1191, 568, 135, 24, 5, 15993, 7536, 1710, 264, 35, 6, 263976, 123704, 27495, 4008, 455, 48, 7, 5189778, 2425320, 533565, 75696, 8050, 720, 63, 8, 118729335, 55403008, 12121920, 1695528, 174615, 14544, 1071, 80, 9
Offset: 0

Views

Author

Paul D. Hanna, Jan 31 2005

Keywords

Comments

Leftmost column is A082163 (enumerates acyclic automata with 2 inputs). The operation SHIFTUP(T) shifts each column of T up 1 row, dropping the elements that occupied the diagonal of T.

Examples

			Rows of T begin:
[1],
[3,2],
[15,8,3],
[114,56,15,4],
[1191,568,135,24,5],
[15993,7536,1710,264,35,6],
[263976,123704,27495,4008,455,48,7],
[5189778,2425320,533565,75696,8050,720,63,8],...
Rows of T^2 begin:
[1],
[9,4],
[84,40,9],
[963,456,105,16],
[13611,6400,1440,216,25],...
Rows of T^2+2*T equals SHIFTUP(T):
[3],
[15,8],
[114,56,15],
[1191,568,135,24],
[15993,7536,1710,264,35],...
G.f. for column 0: 1 = (1-3x) + 3*x/(1-2x)*(1-3x)(1-4x) + 15*x^2/(1-2x)^2*(1-3x)(1-4x)(1-5x) + 114*x^3/(1-2x)^3*(1-3x)(1-4x)(1-5x)(1-6x) + ... + T(n,0)*x^n/(1-2*x)^n*(1-3x)(1-4x)*..*(1-(n+3)x) + ...
G.f. for column 1: 2 = 2*(1-4x) + 8*x/(1-2x)*(1-4x)(1-5x) + 56*x^2/(1-2x)^2*(1-4x)(1-5x)(1-6x) + 568*x^3/(1-2x)^3*(1-4x)(1-5x)(1-6x)(1-7x) + ... + T(n,1)*x^(n-1)/(1-2*x)^(n-1)*(1-4x)(1-5x)*..*(1-(n+3)x) + ...
		

Crossrefs

Programs

  • PARI
    {T(n,k)=if(n
    				

Formula

G.f. for column k: T(k, k) = k+1 = Sum_{n>=k} T(n, k)*x^(n-k)/(1-2*x)^(n-k) * Product_{j=0..n-k} (1-(j+k+3)*x). Diagonalization: T = P*D*P^-1 where P(r, c) = A103247(r, c)/(r-c)! = (-1)^(r-c)*(c^2+2*c)^(r-c)/(r-c)! for r>=c>=1 and [P^-1](r, c) = A103242(r, c)/(r-c)! and D is a diagonal matrix = {1, 2, 3, ...}.

A103242 Unreduced numerators of the elements T(n,k)/(n-k)!, read by rows, of the triangular matrix P^-1, which is the inverse of the matrix defined by P(n,k) = (1-(k+1)^2)^(n-k)/(n-k)! for n >= k >= 1.

Original entry on oeis.org

1, 3, 1, 39, 8, 1, 1206, 176, 15, 1, 69189, 7784, 495, 24, 1, 6416568, 585408, 29430, 1104, 35, 1, 881032059, 67481928, 2791125, 84600, 2135, 48, 1, 168514815360, 11111547520, 389244600, 9841728, 204470, 3744, 63, 1, 42934911510249
Offset: 1

Views

Author

Paul D. Hanna, Feb 02 2005

Keywords

Comments

Define a triangular matrix P where P(n,k) = (-k^2-2*k)^(n-k)/(n-k)!; then M = P*D*P^-1 = A103236 satisfies M^2 + 2*M = SHIFTUP(M) where D is the diagonal matrix consisting of {1,2,3,...}. The operation SHIFTUP(M) shifts each column of M up 1 row. Essentially equal to square array A082171 as a triangular matrix. The first column is A082163 (enumerates acyclic automata with 2 inputs).

Examples

			Rows of unreduced fractions T(n,k)/(n-k)! begin:
  [1/0!],
  [3/1!, 1/0!],
  [39/2!, 8/1!, 1/0!],
  [1206/3!, 176/2!, 15/1!, 1/0!],
  [69189/4!, 7784/3!, 495/2!, 24/1!, 1/0!],
  [6416568/5!, 585408/4!, 29430/3!, 1104/2!, 35/1!, 1/0!], ...
forming the inverse of matrix P where P(n,k) = A103247(n,k)/(n-k)!:
  [1/0!],
  [ -3/1!, 1/0!],
  [9/2!, -8/1!, 1/0!],
  [ -27/3!, 64/2!, -15/1!, 1/0!],
  [81/4!, -512/3!, 225/2!, -24/1!, 1/0!],
  [ -243/5!, 4096/4!, -3375/3!, 576/2!, -35/1!, 1/0!], ...
		

Crossrefs

Programs

  • PARI
    {T(n,k)=my(P);if(n>=k&k>=1, P=matrix(n,n,r,c,if(r>=c,(1-(c+1)^2)^(r-c)/(r-c)!))); return(if(n
    				

Formula

For n > k >= 1: 0 = Sum_{m=k..n} C(n-k, m-k)*(1-(m+1)^2)^(n-m)*T(m, k).
For n > k >= 1: 0 = Sum_{j=k..n} C(n-k, j-k)*(1-(k+1)^2)^(j-k)*T(n, j).

A103243 Unreduced numerators of the elements T(n,k)/(n-k)!, read by rows, of the triangular matrix P^-1, which is the inverse of the matrix defined by P(n,k) = (1-(k+1)^3)^(n-k)/(n-k)! for n >= k >= 1.

Original entry on oeis.org

1, 7, 1, 315, 26, 1, 45682, 2600, 63, 1, 15646589, 675194, 11655, 124, 1, 10567689552, 366349152, 4861458, 37944, 215, 1, 12503979423607, 361884843866, 3882676581, 23641468, 100835, 342, 1, 23841011541867520, 591934698991168, 5318920238688
Offset: 1

Views

Author

Paul D. Hanna, Feb 02 2005

Keywords

Comments

Define triangular matrix P by P(n,k) = (-k^3-3k^2-3k)^(n-k)/(n-k)!, then M = P*D*P^-1 = A103237 satisfies: M^3 + 3M^2 + 3M = SHIFTUP(M) where D is the diagonal matrix consisting of {1,2,3,...}. The operation SHIFTUP(M) shifts each column of M up 1 row. Essentially equal to square array A082172 as a triangular matrix. The first column is A082160 (quasi-acyclic automata with 3 inputs).

Examples

			Rows of unreduced fractions T(n,k)/(n-k)! begin:
  [1/0! ],
  [7/1!, 1/0! ],
  [315/2!, 26/1!, 1/0! ],
  [45682/3!, 2600/2!, 63/1!, 1/0! ],
  [15646589/4!, 675194/3!, 11655/2!, 124/1!, 1/0! ],
  [10567689552/5!, 366349152/4!, 4861458/3!, 37944/2!, 215/1!, 1/0! ], ...
forming the inverse of matrix P where P(n,k) = A103247(n,k)/(n-k)!:
  [1/0! ],
  [ -7/1!, 1/0! ],
  [49/2!, -26/1!, 1/0! ],
  [ -343/3!, 676/2!, -63/1!, 1/0! ],
  [2401/4!, -17576/3!, 3969/2!, -124/1!, 1/0! ],
  [ -16807/5!, 456976/4!, -250047/3!, 15376/2!, -215/1!, 1/0! ], ...
		

Crossrefs

Programs

  • PARI
    {T(n,k)=my(P);if(n>=k&k>=1, P=matrix(n,n,r,c,if(r>=c,(1-(c+1)^3)^(r-c)/(r-c)!))); return(if(n
    				

Formula

For n > k >= 1: 0 = Sum_{m=k..n} C(n-k, m-k)*(1-(m+1)^3)^(n-m)*T(m, k). For n > k >= 1: 0 = Sum_{j=k..n} C(n-k, j-k)*(1-(k+1)^3)^(j-k)*T(n, j).

A103407 Triangle of absolute values of the coefficients (in descending powers) of the characteristic polynomials of n X n matrices with 3's on the main diagonal and 1's elsewhere.

Original entry on oeis.org

1, 1, 3, 1, 6, 8, 1, 9, 24, 20, 1, 12, 48, 80, 48, 1, 15, 80, 200, 240, 112, 1, 18, 120, 400, 720, 672, 256, 1, 21, 168, 700, 1680, 2352, 1792, 576, 1, 24, 224, 1120, 3360, 6272, 7168, 4608, 1280, 1, 27, 288, 1680, 6048, 14112, 21504, 20736, 11520, 2816, 1, 30
Offset: 0

Views

Author

Gary W. Adamson, Feb 04 2005

Keywords

Examples

			3rd row (1, 9, 24, 20) with alternating signs = characteristic polynomial 3 X 3 matrix [3 1 1 / 1 3 1 / 1 1 3], x^3 - 9x^2 + 24x - 20.
		

Crossrefs

Row sums are A006234: 1, 4, 15, 54, 189... Rightmost terms in each row = A001792: 1, 3, 8, 20, 48, 112, 256...(row sums of A103406, the analogous triangle with all 2's in the generating matrix.)
See A103247 for another version.

Extensions

Extended and edited by John W. Layman, Mar 17 2005
Showing 1-5 of 5 results.