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 1-3 of 3 results.

A111975 Triangle P, read by rows, that satisfies [P^2](n,k) = P(n+1,k+1) for n>=k>=0, also [P^(2*m)](n,k) = [P^m](n+1,k+1) for all m, where [P^m](n,k) denotes the element at row n, column k, of the matrix power m of P, with P(k,k)=1 and P(k+2,2)=P(k+2,0) for k>=0.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 4, 4, 4, 1, 16, 16, 16, 8, 1, 96, 96, 96, 64, 16, 1, 896, 896, 896, 704, 256, 32, 1, 13568, 13568, 13568, 11776, 5504, 1024, 64, 1, 345088, 345088, 345088, 317952, 178176, 43776, 4096, 128, 1, 15112192, 15112192, 15112192, 14422016
Offset: 0

Views

Author

Paul D. Hanna, Aug 24 2005

Keywords

Comments

Terms of column 0, column 1 and column 2 in row n are equal for n>2.

Examples

			Triangle P begins:
1;
1,1;
1,2,1;
4,4,4,1;
16,16,16,8,1;
96,96,96,64,16,1;
896,896,896,704,256,32,1;
13568,13568,13568,11776,5504,1024,64,1;
345088,345088,345088,317952,178176,43776,4096,128,1; ...
where P^2 shifts columns left and up one place:
1;
2,1;
4,4,1;
16,16,8,1;
96,96,64,16,1; ...
The matrix inverse, P^-1, equals signed P:
1;
-1,1;
1,-2,1;
-4,4,-4,1;
16,-16,16,-8,1; ...
		

Crossrefs

Cf. A111976 (column 0), A111977 (row sums), A111978 (matrix log), A098539 (variant), A078536 (variant).

Programs

  • PARI
    P(n,k,q=2)=local(A=Mat(1),B);if(n2,(A^q)[i-1,2],1), B[i,j]=(A^q)[i-1,j-1]));));A=B);return(A[n+1,k+1]))

Formula

The g.f. of column k of P^m (ignoring leading zeros) equals: 1 + Sum_{n>=1} (m*2^k)^n/n! * Product_{j=0..n-1} L(2^j*x) where L(x) is the g.f. of column 0 of the matrix log of P (A111979) and satisfies: x-x^2 = Sum_{j>=1}(1-2^j*x)*Prod_{i=0..j-1}L(2^i*x).

A111976 Column 0 of triangle A111975, which shifts columns left and up under matrix square.

Original entry on oeis.org

1, 1, 1, 4, 16, 96, 896, 13568, 345088, 15112192, 1159913472, 158164664320, 38737429987328, 17197276791701504, 13946909814794223616, 20801835304287183306752, 57394078732651064041930752
Offset: 0

Views

Author

Paul D. Hanna, Aug 25 2005

Keywords

Examples

			G.f. A(x) = 1 + x + x^2 + 4*x^3 + 16*x^4 + 96*x^5 + 896*x^6 +...
= 1 + L(x) + L(x)*L(2*x)/2! + L(x)*L(2*x)*L(2^2*x)/3! +...
where L(x) = x + 16/3!*x^3 + 1536/5!*x^5 - 319488/7!*x^7 +-...
		

Crossrefs

Cf. A111975 (triangle), A111979.

Programs

  • PARI
    {a(n,q=2)=local(A=Mat(1),B);if(n<0,0, for(m=1,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=1,if(j==1,B[i,j]=if(i>2,(A^q)[i-1,2],1), B[i,j]=(A^q)[i-1,j-1]));));A=B);return(A[n+1,1]))}

Formula

G.f.: A(x) = 1 + Sum_{n>=1} (1/n!)*Product_{j=0..n-1} L(2^j*x) where L(x) satisfies: x-x^2 = Sum_{j>=1}(1-2^j*x)*Prod_{i=0..j-1}L(2^i*x); and L(x) equals the g.f. of column 0 of the matrix log of A111975 (A111979).

A111978 Matrix log of triangle A111975, which shifts columns left and up under matrix square; these terms are the result of multiplying each element in row n and column k by (n-k)!.

Original entry on oeis.org

0, 1, 0, 0, 2, 0, 16, 0, 4, 0, 0, 32, 0, 8, 0, 1536, 0, 64, 0, 16, 0, 0, 3072, 0, 128, 0, 32, 0, -319488, 0, 6144, 0, 256, 0, 64, 0, 0, -638976, 0, 12288, 0, 512, 0, 128, 0, 36007575552, 0, -1277952, 0, 24576, 0, 1024, 0, 256, 0, 0, 72015151104, 0, -2555904, 0, 49152, 0, 2048, 0, 512, 0
Offset: 0

Views

Author

Paul D. Hanna, Aug 25 2005

Keywords

Comments

Column k equals 2^k multiplied by column 0 (A111979) when ignoring zeros above the diagonal.

Examples

			Matrix log of A111975, with factorial denominators, begins:
0;
1/1!, 0;
0/2!, 2/1!, 0;
16/3!, 0/2!, 4/1!, 0;
0/4!, 32/3!, 0/2!, 8/1!, 0;
1536/5!, 0/4!, 64/3!, 0/2!, 16/1!, 0;
0/6!, 3072/5!, 0/4!, 128/3!, 0/2!, 32/1!, 0;
-319488/7!, 0/6!, 6144/5!, 0/4!, 256/3!, 0/2!, 64/1!, 0; ...
		

Crossrefs

Cf. A111975 (triangle), A111979 (column 0).

Programs

  • PARI
    T(n,k,q=2)=local(A=Mat(1),B);if(n2,(A^q)[i-1,2],1), B[i,j]=(A^q)[i-1,j-1]));));A=B); B=sum(i=1,#A,-(A^0-A)^i/i);return((n-k)!*B[n+1,k+1]))

Formula

T(n, k) = 2^k*T(n-k, 0) = 2^k*A111979(n-k) for n>=k>=0.
Showing 1-3 of 3 results.