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.

A113289 Row sums of triangle A113288.

Original entry on oeis.org

1, -1, 4, -15, 36, -119, 302, -911, 2440, -7199, 20186, -60359, 177204, -546615, 1683286, -5401759, 17456128, -58447151, 197925490, -691264279, 2446636396, -8897012871, 32811147054, -123933345455, 474792813176, -1858243857599, 7375013350282, -29840434526951
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Crossrefs

A113287 Triangle T, read by rows, where row n of T equals row n of matrix (n+1)-th power of triangle A112555.

Original entry on oeis.org

1, 2, 1, -3, 0, 1, 4, 4, 4, 1, -5, -10, -10, 0, 1, 6, 18, 24, 12, 6, 1, -7, -28, -49, -42, -21, 0, 1, 8, 40, 88, 104, 72, 24, 8, 1, -9, -54, -144, -216, -198, -108, -36, 0, 1, 10, 70, 220, 400, 460, 340, 160, 40, 10, 1, -11, -88, -319, -682, -946, -880, -550, -220, -55, 0, 1
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Comments

Remarkably, the matrix logarithm (A113290) is an integer triangle. Matrix m-th power of A112555 = I + m*(A112555 - I) where I = identity matrix.

Examples

			Triangle begins:
1;
2,1;
-3,0,1;
4,4,4,1;
-5,-10,-10,0,1;
6,18,24,12,6,1;
-7,-28,-49,-42,-21,0,1;
8,40,88,104,72,24,8,1;
-9,-54,-144,-216,-198,-108,-36,0,1;
10,70,220,400,460,340,160,40,10,1; ...
		

Crossrefs

Cf. A112555, A113288 (inverse), A113290 (log), A113291, A072374.

Programs

  • PARI
    {T(n,k)=local(x=X+X*O(X^n),y=Y+Y*O(Y^k)); polcoeff(polcoeff(1/(1-x*y)+x*(x+2)/((1-x*y)^2*(1+x+x*y)^2),n,X),k,Y)}

Formula

G.f.: A(x, y) = 1/(1-x*y) + x*(x+2)/((1-x*y)^2*(1+x+x*y)^2).

A113290 Matrix logarithm of triangle A113287.

Original entry on oeis.org

0, 2, 0, -3, 0, 0, 6, 4, 4, 0, -10, -10, -10, 0, 0, 19, 24, 30, 12, 6, 0, -35, -49, -70, -42, -21, 0, 0, 72, 104, 164, 128, 84, 24, 8, 0, -150, -216, -360, -324, -252, -108, -36, 0, 0, 343, 480, 820, 800, 710, 400, 180, 40, 10, 0, -803, -1089, -1870, -1892, -1826, -1210, -660, -220, -55, 0, 0
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Examples

			Triangle begins:
0;
2,0;
-3,0,0;
6,4,4,0;
-10,-10,-10,0,0;
19,24,30,12,6,0;
-35,-49,-70,-42,-21,0,0;
72,104,164,128,84,24,8,0;
-150,-216,-360,-324,-252,-108,-36,0,0;
343,480,820,800,710,400,180,40,10,0; ...
		

Crossrefs

Cf. A113287, A113288, A113291 (column 1), A113292 (column 0), A072374.

Programs

  • PARI
    {T(n,k)=local(x=X+O(X^(n+2)),y=Y+O(Y^(n+2)),M=matrix(n+1,n+1,r,c,if(r==c,1, if(r>c,r*polcoeff(polcoeff(1/(1-x*y)+x/((1-x*y)*(1+x+x*y)),r-1,X),c-1,Y))))); if(n
    				

Formula

T(n, 1) = (n+1)*A113291(n).

A113291 a(n) = A113290(n,1)/(n+1) for n>=0, where A113290 is the matrix log of triangle A113287.

Original entry on oeis.org

0, 0, 0, 1, -2, 4, -7, 13, -24, 48, -99, 221, -512, 1268, -3247, 8773, -24400, 70896, -211347, 653541, -2068472, 6755684, -22541135, 77305981, -270435640, 969413776, -3539893923, 13212871629, -50180362320, 194412817844, -765590169935, 3070433223317
Offset: 0

Views

Author

Paul D. Hanna, Oct 23 2005

Keywords

Crossrefs

Programs

  • PARI
    a(n)=if(n<3,0,(-1)^(n-3)*sum(k=0,n-3,sum(j=0,k\2,(k-j)!/(k-2*j)!)))

Formula

G.f. satisfies: A(x) = x^3*((2+x)/(1+x) + (1+x)*A'(x))/(2+3*x+2*x^2). a(n+3) = (-1)^n*Sum_{k=0..n} Sum{j=0..[k/2]} (k-j)!/(k-2*j)! for n>=0. a(n+3) = -a(n+2) + (-1)^n*A072374(n) for n>=1.
Showing 1-4 of 4 results.