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.

A185675 Riordan array ( (1+x)/(1-x-x^2), x*A000108(x) ).

Original entry on oeis.org

1, 2, 1, 3, 3, 1, 5, 7, 4, 1, 8, 17, 12, 5, 1, 13, 43, 35, 18, 6, 1, 21, 116, 103, 60, 25, 7, 1, 34, 333, 312, 196, 93, 33, 8, 1, 55, 1010, 976, 643, 331, 135, 42, 9, 1, 89, 3202, 3147, 2137, 1161, 518, 187, 52, 10, 1, 144, 10504, 10415, 7213, 4066, 1929, 768, 250, 63, 11, 1
Offset: 0

Views

Author

Vladimir Kruchinin, Feb 09 2011

Keywords

Examples

			Triangle begins:
   1;
   2,   1;
   3,   3,   1;
   5,   7,   4,   1;
   8,  17,  12,   5,   1;
  13,  43,  35,  18,   6,   1;
  21, 116, 103,  60,  25,   7,   1;
  34, 333, 312, 196,  93,  33,   8,   1;
Production matrix begins:
    2, 1;
   -1, 1, 1;
    2, 1, 1, 1;
   -3, 1, 1, 1, 1;
    5, 1, 1, 1, 1, 1;
   -8, 1, 1, 1, 1, 1, 1;
   13, 1, 1, 1, 1, 1, 1, 1;
  -21, 1, 1, 1, 1, 1, 1, 1, 1;
  ... _Philippe Deléham_, Sep 21 2014
		

Programs

  • Maple
    A185675 := proc(n,k) if n = k then 1; elif k = 0 then combinat[fibonacci](n+2) ; else k*add(1/(n-i)*add(binomial(j,i+1-j)*binomial(2*n-2*i-k-1,n-i-1), j=1..i+1), i=0..n-k) ; end if; end proc:
    seq(seq(A185675(n,k),k=0..n),n=0..15) ; # R. J. Mathar, Feb 10 2011
  • Mathematica
    r[n_, k_] := k*Sum[Binomial[2*(n - i) - k - 1, n - i - 1]*Fibonacci[i + 2]/(n - i), {i, 0, n - k}]; r[n_, 0] := Fibonacci[n + 2]; r[n_, n_] := 1; Table[r[n, k], {n, 0, 3}, {k, 0, n}] // Flatten (* Jean-François Alcover, Feb 21 2013; modified by G. C. Greubel, Jul 10 2017 *)

Formula

R(n,k) = k*Sum_{i=0..n-k}(Sum_{j=1..i+1}binomial(j,i+1-j))*binomial(2*(n-i)-k-1,n-i-1)/(n-i), k>0.
R(n,0) = A000045(n+2).