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.

A192406 Main diagonal of square array A192404, with a(0)=1.

Original entry on oeis.org

1, 1, 2, 14, 114, 1131, 12393, 146712, 1838094, 24088842, 327526513, 4593918125, 66198455671, 977113573208, 14741071612583, 226941948201964, 3561383719180100, 56926946565867437, 926444637518092848, 15347533201937448776, 258809102457332568964
Offset: 0

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Author

Paul D. Hanna, Jun 30 2011

Keywords

Comments

The g.f. G(x,y) of square array A192404 satisfies the relations:
G(x,y) = 1 + Sum{n>=1} x^n*y*G(x,y)^n/(1 - y*G(x,y)^(2*n)),
G(x,y) = 1 + Sum{n>=1} y^n*x*G(x,y)^(2*n-1)/(1 - x*G(x,y)^(2*n-1)),
where G(x,y) = 1 + Sum_{n>=1,k>=1} A192404(n,k)*x^n*y^k, and this sequence consists of the diagonal terms a(n) = A192404(n,n); what then is the g.f. of this sequence?

Examples

			G.f.: A(x) = 1 + x + 2*x^2 + 14*x^3 + 114*x^4 + 1131*x^5 + 12393*x^6 +...
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x*y);for(i=1,n,A=1+sum(m=1,n,x^m*y*A^m/(1-y*A^(2*m)+x*O(x^n)+y*O(y^n))));polcoeff(polcoeff(A,n,x),n,y)}
    
  • PARI
    {a(n)=local(A=1+x*y);for(i=1,n,A=1+sum(m=1,n,y^m*x*A^(2*m-1)/(1-x*A^(2*m-1)+x*O(x^n)+y*O(y^n))));polcoeff(polcoeff(A,n,y),n,x)}

A192407 A diagonal of square array A192404.

Original entry on oeis.org

1, 4, 31, 291, 3092, 35839, 441925, 5721008, 77009425, 1071034612, 15319883964, 224628789200, 3368096726910, 51552652046550, 804490751228163, 12788591015038781, 206977224029107906, 3409582505289727239, 57165456138722305360
Offset: 1

Views

Author

Paul D. Hanna, Jun 30 2011

Keywords

Comments

The g.f. G(x,y) of square array A192404 satisfies the relations:
G(x,y) = 1 + Sum{n>=1} x^n*y*G(x,y)^n/(1 - y*G(x,y)^(2*n)),
G(x,y) = 1 + Sum{n>=1} y^n*x*G(x,y)^(2*n-1)/(1 - x*G(x,y)^(2*n-1)),
where G(x,y) = 1 + Sum_{n>=1,k>=1} A192404(n,k)*x^n*y^k, and this sequence consists of the diagonal terms a(n) = A192404(n+1,n) for n>=1.

Examples

			G.f.: A(x) = x + 4*x^2 + 31*x^3 + 291*x^4 + 3092*x^5 + 35839*x^6 +...
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=x*y);for(i=1,n+1,A=1+sum(m=1,n+1,x^m*y*A^m/(1-y*A^(2*m)+x*O(x^n)+y*O(y^n))));polcoeff(polcoeff(A,n+1,x),n,y)}
    
  • PARI
    {a(n)=local(A=x*y);for(i=1,n+1,A=1+sum(m=1,n+1,y^m*x*A^(2*m-1)/(1-x*A^(2*m-1)+x*O(x^n)+y*O(y^n))));polcoeff(polcoeff(A,n,y),n+1,x)}

A192405 G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^(n+1) * A(x)^n/(1 - x*A(x)^(2*n)).

Original entry on oeis.org

1, 0, 1, 2, 4, 11, 33, 99, 310, 1016, 3413, 11682, 40751, 144476, 519013, 1886311, 6928012, 25684055, 96020957, 361742039, 1372442092, 5241062187, 20136335035, 77806111700, 302259125863, 1180207733657, 4630733662020, 18254415188073, 72283753111667
Offset: 0

Views

Author

Paul D. Hanna, Jun 30 2011

Keywords

Comments

Related q-series identity:
Sum_{n>=1} z^n*y*q^n/(1-y*q^(2*n)) = Sum_{n>=1} y^n*z*q^(2*n-1)/(1-z*q^(2*n-1)); here q=A(x), y=x, z=x.

Examples

			G.f.: A(x) = 1 + x^2 + 2*x^3 + 4*x^4 + 11*x^5 + 33*x^6 + 99*x^7 +...
which satisfies the following relations:
A(x) = 1 + x^2*A(x)/(1-x*A(x)^2) + x^3*A(x)^2/(1-x*A(x)^4) + x^4*A(x)^3/(1-x*A(x)^6) +...
A(x) = 1 + x^2*A(x)/(1-x*A(x)) + x^3*A(x)^3/(1-x*A(x)^3) + x^4*A(x)^5/(1-x*A(x)^5) +...
A(x) = 1 + x^2*A(x) + x^3*A(x)^3*(1 + 1/A(x)) + x^4*A(x)^6*(1 + 1/A(x) + 1/A(x)^3) + x^5*A(x)^10*(1 + 1/A(x) + 1/A(x)^3 + 1/A(x)^6) +...
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x^2);for(i=1,n,A=1+x*sum(m=1,n,x^m*A^m/(1-x*A^(2*m)+x*O(x^n))));polcoeff(A,n)}
    
  • PARI
    {a(n)=local(A=1+x^2);for(i=1,n,A=1+x*sum(m=1,n,x^m*A^(2*m-1)/(1-x*A^(2*m-1)+x*O(x^n))));polcoeff(A,n)}
    
  • PARI
    {a(n)=local(A=1+x);for(i=1,n,A=1+sum(m=1,n,x^(m+1)*A^(m*(m+1)/2)*sum(k=0,m-1,(A+x*O(x^n))^(-k*(k+1)/2) ) ) );polcoeff(A,n)}

Formula

G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^(n+1)*A(x)^(2*n-1)/(1 - x*A(x)^(2*n-1)).
G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^(n+1)*A(x)^(n*(n+1)/2) * Sum_{k=0..n-1} A(x)^(-k*(k+1)/2).
Equals the antidiagonal sums of square array A192404.
Showing 1-3 of 3 results.