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.

A172400 G.f.: 1/(1-x) = (1-x*y) * Sum_{k>=0} Sum_{n>=k} T(n,k)*x^n*y^k/(1+x)^(2^n-2^k).

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 6, 3, 1, 1, 32, 16, 5, 1, 1, 332, 166, 51, 9, 1, 1, 6928, 3464, 1059, 181, 17, 1, 1, 292334, 146167, 44620, 7557, 681, 33, 1, 1, 24875760, 12437880, 3795202, 641035, 57097, 2641, 65, 1, 1, 4254812880, 2127406440, 649054326, 109540639
Offset: 0

Views

Author

Paul D. Hanna, Feb 01 2010

Keywords

Examples

			Triangle begins:
1;
1, 1;
2, 1, 1;
6, 3, 1, 1;
32, 16, 5, 1, 1;
332, 166, 51, 9, 1, 1;
6928, 3464, 1059, 181, 17, 1, 1;
292334, 146167, 44620, 7557, 681, 33, 1, 1;
24875760, 12437880, 3795202, 641035, 57097, 2641, 65, 1, 1;
4254812880, 2127406440, 649054326, 109540639, 9723237, 443921, 10401, 129, 1, 1; ...
Matrix inverse of this triangle begins:
1;
-1,1;
-1,-1,1;
-2,-2,-1,1;
-9,-9,-4,-1,1;
-88,-88,-38,-8,-1,1;
-1802,-1802,-772,-156,-16,-1,1;
-75598,-75598,-32313,-6456,-632,-32,-1,1; ...
in which unsigned column 0 = A001192, number of full sets of size n.
		

Crossrefs

Cf. A001192, columns: A172401, A172402, A172403.

Programs

  • PARI
    {T(n,k)=if(n==k,1,polcoeff(-(1-x)*sum(m=0,n-k-1,T(m+k,k)*x^m/(1+x +x*O(x^n))^(2^(m+k)-2^k)),n-k))}
    
  • PARI
    {T(n,k)=local(M,N); M=matrix(n+1,n+1,r,c,if(r>=c,polcoeff(1/(1-x+O(x^(r-c+1)))^1*(1+x)^(2^(r-1)-2^(c-1)),r-c))); N=matrix(n+1,n+1,r,c,if(r>=c,polcoeff(1/(1-x+O(x^(r-c+1)))^2*(1+x)^(2^(r-1)-2^(c-1)),r-c))); (M^-1*N)[n+1,k+1]}

Formula

Unsigned column 0 of matrix inverse forms A001192, which is the number of full sets of size n.