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.

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A103238 Triangular matrix T, read by rows, that satisfies: T^2 + T = SHIFTUP(T), also T^(n+1) + 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, 2, 2, 8, 6, 3, 52, 36, 12, 4, 480, 324, 96, 20, 5, 5816, 3888, 1104, 200, 30, 6, 87936, 58536, 16320, 2800, 360, 42, 7, 1601728, 1064016, 294048, 49200, 5940, 588, 56, 8, 34251520, 22728384, 6252288, 1032800, 120960, 11172, 896, 72, 9, 843099616
Offset: 0

Views

Author

Paul D. Hanna, Jan 31 2005

Keywords

Comments

Leftmost column is A103239. 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],
[2,2],
[8,6,3],
[52,36,12,4],
[480,324,96,20,5],
[5816,3888,1104,200,30,6],
[87936,58536,16320,2800,360,42,7],
[1601728,1064016,294048,49200,5940,588,56,8],...
Rows of T^2 begin:
[1],
[6,4],
[44,30,9],
[428,288,84,16],
[5336,3564,1008,180,25],...
Then T^2 + T = SHIFTUP(T):
[2],
[8,6],
[52,36,12],
[480,324,96,20],
[5816,3888,1104,200,30],...
G.f. for column 0: 1 = (1-2x) + 2*x/(1-x)*(1-2x)(1-3x) + 8*x^2/(1-x)^2*(1-2x)(1-3x)(1-4x) + 52*x^3/(1-x)^3*(1-2x)(1-3x)(1-4x)(1-5x) + ... + T(n,0)*x^n/(1-x)^n*(1-2x)(1-3x)*..*(1-(n+2)x) + ...
G.f. for column 1: 2 = 2*(1-3x) + 6*x/(1-x)*(1-3x)(1-4x) + 36*x^2/(1-x)^2*(1-3x)(1-4x)(1-5x) + 324*x^3/(1-x)^3*(1-3x)(1-4x)(1-5x)(1-6x) + ... + T(n,1)*x^(n-1)/(1-x)^(n-1)*(1-3x)(1-4x)*..*(1-(n+2)x) + ...
		

Crossrefs

Programs

  • PARI
    /* Using Matrix Diagonalization Formula: */ T(n,k)=my(P,D);D=matrix(n+1,n+1,r,c,if(r==c,r)); P=matrix(n+1,n+1,r,c,if(r>=c,(-1)^(r-c)*(c^2+c)^(r-c)/(r-c)!)); return(if(n
    				
  • PARI
    /* Using Generating Function for Columns: */ 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-x)^(n-k) * Product_{j=0..n-k} (1-(j+k+2)*x). Diagonalization: T = P*D*P^-1 where P(r, c) = A103249(r, c)/(r-c)! = (-1)^(r-c)*(c^2+c)^(r-c)/(r-c)! for r>=c>=1 and [P^-1](r, c) = A103244(r, c)/(r-c)! and D is a diagonal matrix = {1, 2, 3, ...}.

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).
Showing 1-2 of 2 results.