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.

A135898 Triangle, read by rows equal to the matrix product P^-1*R, where P = A135880 and R = A135894; P^-1*R equals triangle P shifted right one column.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 2, 1, 0, 6, 7, 3, 1, 0, 25, 34, 15, 4, 1, 0, 138, 215, 99, 26, 5, 1, 0, 970, 1698, 814, 216, 40, 6, 1, 0, 8390, 16220, 8057, 2171, 400, 57, 7, 1, 0, 86796, 182714, 93627, 25628, 4740, 666, 77, 8, 1, 0, 1049546, 2378780, 1252752, 348050, 64805
Offset: 0

Views

Author

Paul D. Hanna, Dec 15 2007

Keywords

Examples

			Triangle begins:
1;
0, 1;
0, 1, 1;
0, 2, 2, 1;
0, 6, 7, 3, 1;
0, 25, 34, 15, 4, 1;
0, 138, 215, 99, 26, 5, 1;
0, 970, 1698, 814, 216, 40, 6, 1;
0, 8390, 16220, 8057, 2171, 400, 57, 7, 1;
0, 86796, 182714, 93627, 25628, 4740, 666, 77, 8, 1; ...
This triangle equals matrix product P^-1*R,
which equals triangle P shifted right one column,
where P = A135880 begins:
1;
1, 1;
2, 2, 1;
6, 7, 3, 1;
25, 34, 15, 4, 1;
138, 215, 99, 26, 5, 1;
970, 1698, 814, 216, 40, 6, 1; ...
and Q = P^2 = A135885 begins:
1;
2, 1;
6, 4, 1;
25, 20, 6, 1;
138, 126, 42, 8, 1;
970, 980, 351, 72, 10, 1;
8390, 9186, 3470, 748, 110, 12, 1; ...
and R = A135894 begins:
1;
1, 1;
2, 3, 1;
6, 12, 5, 1;
25, 63, 30, 7, 1;
138, 421, 220, 56, 9, 1;
970, 3472, 1945, 525, 90, 11, 1; ...
where column k of R equals column 0 of P^(2k+1),
and column k of Q=P^2 equals column 0 of P^(2k+2), for k>=0.
		

Crossrefs

Cf. A135880 (P), A135885 (Q=P^2), A135894 (R); A135899 (P*R^-1*P), A135900 (R^-1*Q).

Programs

  • PARI
    {T(n,k)=local(P=Mat(1),R=Mat(1),PShR);if(n>0,for(i=0,n, PShR=matrix(#P,#P, r,c, if(r>=c,if(r==c,1,if(c==1,0,P[r-1,c-1]))));R=P*PShR; R=matrix(#P+1, #P+1, r,c, if(r>=c, if(r<#P+1,R[r,c], if(c==1,(P^2)[ #P,1],(P^(2*c-1))[r-c+1,1])))); P=matrix(#R, #R, r,c, if(r>=c, if(r<#R,P[r,c], (R^c)[r-c+1,1])))));(P^-1*R)[n+1,k+1]}