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 1-2 of 2 results.

A173403 Inverse binomial transform of A002416.

Original entry on oeis.org

1, 1, 13, 469, 63577, 33231721, 68519123173, 562469619451069, 18442242396353040817, 2417685638793025070212561, 1267626422541873052658376446653, 2658442047546208031914776455678477989, 22300713297142388711251601783864453690641417
Offset: 0

Views

Author

Brian Drake, Feb 17 2010

Keywords

Comments

a(n) is the number of n X n matrices of 0's and 1's with the property that there is no index k such that both the k-th column and the k-th row consist of all zeros.
a(n) is the number of binary relations on n labeled vertices with no vertex of indegree and outdegree = 0. - Geoffrey Critzer, Oct 02 2012

References

  • E. A. Bender and S. G. Williamson, Foundations of Combinatorics with Applications, Dover, 2005, exercise 4.1.6.

Crossrefs

Programs

  • Maple
    N:=8: seq( sum(binomial(n,i)*2^((n-i)^2)*(-1)^(i), i=0..n), n=0..N);
  • Mathematica
    Table[Sum[(-1)^k Binomial[n,k] 2^(n-k)^2,{k,0,n}],{n,0,20}]  (* Geoffrey Critzer, Oct 02 2012 *)

Formula

a(n) = Sum_{k=0..n} (-1)^k*binomial(n,k)*2^((n-k)^2).
a(n) ~ 2^(n^2). - Vaclav Kotesovec, Oct 30 2017

A006898 a(n) = Sum_{k=0..n} C(n,k)*2^(k*(k+1)/2).

Original entry on oeis.org

1, 3, 13, 95, 1337, 38619, 2310533, 283841911, 70927591153, 35812691480115, 36383765777442685, 74185239630793429775, 303119284294591169426729, 2479814853198140771706795531, 40599509058360322571947638063605
Offset: 0

Views

Author

Keywords

Comments

First differences of A006896.

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Mathematica
    Table[Sum[Binomial[n,k]2^((k(k+1))/2),{k,0,n}],{n,0,20}] (* Harvey P. Dale, Apr 01 2023 *)
  • PARI
    a(n)=sum(k=0,n,binomial(n,k)*2^(k*(k+1)/2)) \\ Paul D. Hanna, Apr 10 2009

Formula

a(n) ~ 2^(n*(n+1)/2). - Vaclav Kotesovec, Nov 27 2017

Extensions

Formula and more terms from Vladeta Jovovic, Sep 20 2003
Edited by N. J. A. Sloane, Apr 12 2009 at the suggestion of Vladeta Jovovic
Showing 1-2 of 2 results.