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.

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A192174 Triangle T(n,k) of the coefficients [x^(n-k)] of the polynomial p(0,x)=-1, p(1,x)=x and p(n,x) = x*p(n-1,x) - p(n-2,x) in row n, column k.

Original entry on oeis.org

-1, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, -1, 0, -1, 1, 0, -2, 0, -1, 0, 1, 0, -3, 0, 0, 0, 1, 1, 0, -4, 0, 2, 0, 2, 0, 1, 0, -5, 0, 5, 0, 2, 0, -1, 1, 0, -6, 0, 9, 0, 0, 0, -3, 0, 1, 0, -7, 0, 14, 0, -5, 0, -5, 0, 1, 1, 0, -8, 0, 20, 0, -14, 0, -5, 0, 4, 0
Offset: 0

Views

Author

Paul Curtz, Jun 24 2011

Keywords

Comments

Consider the Catalan triangle A009766 antisymmetrically extended by a mirror along the diagonal (see also A176239):
0, -1, -1, -1, -1, -1, -1, -1,
1, 0, -1, -2, -3, -4, -5, -6,
1, 1, 0, -2, -5, -9, -14, -20,
1, 2, 2, 0, -5, -14, -28, -48,
1, 3, 5, 5, 0, -14, -42, -90,
1, 4, 9, 14, 14, 0, -42, -132,
1, 5, 14, 28, 42, 42, 0, -132,
1, 6, 20, 48, 90, 132, 132, 0.
The rows in this array are essentially the columns of T(n,k).

Examples

			Triangle begins
  -1;      # -1
   1,  0;      # x
   1,  0,  1;      # x^2+1
   1,  0,  0,  0;      # x^3
   1,  0, -1,  0, -1;      # x^4-x^2-1
   1,  0, -2,  0, -1,  0;
   1,  0, -3,  0,  0,  0,  1;
   1,  0, -4,  0,  2,  0,  2,  0;
   1,  0, -5,  0,  5,  0,  2,  0, -1;
   1,  0, -6,  0,  9,  0,  0,  0, -3,  0;
   1,  0, -7,  0, 14,  0, -5,  0, -5,  0,  1;
   1,  0, -8,  0, 20,  0,-14,  0, -5,  0,  4,  0;
   1,  0, -9,  0, 27,  0,-28,  0,  0,  0,  9,  0, -1;
		

Crossrefs

Cf. A194084. - Paul Curtz, Aug 16 2011

Programs

  • Maple
    p:= proc(n,x) option remember: if n=0 then -1 elif n=1 then x elif n>=2 then x*procname(n-1,x)-procname(n-2,x) fi: end: A192174 := proc(n,k): coeff(p(n,x),x,n-k): end: seq(seq(A192174(n,k),k=0..n), n=0..11); # Johannes W. Meijer, Aug 21 2011

Formula

Sum_{k=0..n} T(n,k) = A057079(n-1).
Apparently T(3s,2s-2) = (-1)^(s+1)*A000245(s), s >= 1.

A176511 From Bernoulli twin numbers to Catalan numbers arrays (*).First part.We consider array, from Bernoulli twin numbers A051716/A051717 mixed with their companion A172083/A051717 BTC(n)=1,1,-1/2,-3/2,-1/3,2/3,-1/6,-1/6, and successive differences ,named BTC1. a(n) are numerators of BTC(n).Denominators are (double A051717)=1,1,2,2,3,3,6,6,30,30,30,30,.

Original entry on oeis.org

1, 1, -1, -3, -1, 2, -1, -1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, 1, 1, 5, 5
Offset: 0

Views

Author

Paul Curtz, Apr 19 2010

Keywords

Comments

(*) Even case:ECT(n) in A176239. BTC(n) are not Bi-Bernoulli numbers (absolute values of mixed sequences are not the same like BB1(n) in A176144 or BB2(n) in A176184). Rows of array BTC1: 1) 1,1,-1/2,-3/2,-1/3,2/3,-1/6,-1/6,-1/30,-1/30,1/30,1/30,1/42,1/42,; 2) 0,-3/2,-1,7/6,1,-5/6,0,2/15,0,2/15,0; 3) -3/2,1/2,13/6,-1/6,-11/6,5/6,2/15,-2/15,2/15,-2/15; 4) 2,5/3,-7/3,-5/3,8/3,-7/10,-4/15,4/15,-4/15; 5) -1/3,-4,2/3,13/3,-101/30,13/30,8/15,-8/15; 6) -11/3,14/3,11/3,-77/10,19/5,1/10,-16/15; 7) 25/3,-1, -341/30,23/2,-37/10,-29/30; 8) -28/3,-311/30,343/15,. Correction:in A176150 last term (-517) is false.

A176784 From Bernoulli twin numbers to Catalan numbers arrays.Second part.Consider array from companion of Bernoulli twin numbers A172083/A051717 mixed with A051716/A051717 BCT(n)=1,1,-3/2,-1/2,2/3,-1/3,-1/6,-1/6, with successive differences,named BCT1.a(n) are numerators of BCT(n).Denominators (double A051717)=1,1,2,2,3,3,6,6,30,30,30,30,.

Original entry on oeis.org

1, 1, -3, -1, 2, -1, -1, -1, -1, -1, 1, 1, 1, 1, -1, -1, -1, -1, 1, 1, 5, 5
Offset: 0

Views

Author

Paul Curtz, Apr 26 2010

Keywords

Comments

a(n) is A176511 (companion) with A176511(2),A176511(3), A176511(4),A176511(5) swapped by pairs.Rows of BCT1: 1) 1,1,-3/2,-1/2,2/3,-1/3,-1/6,-1/6; 2) 0,-5/2,1,7/6,-1,1/6,0,2/15; 3) -5/2,7/2,1/6,-13/6,7/6,-1/6,2/15,-2/15; 4) 6,-10/3,-7/3,10/3,-4/3,3/10,-4/15,4/15; 5) -28/3,1,17/3,-14/3,49/30,-17/30,8/15,-8/15; 6) 31/3,14/3,-31/3,63/10,-11/5,11/10,16/15; 7) -17/3,-15,499/30,-17/2,33/10,-1/30; 8) -28/3,949/30,-377/15; .Now we subtract first part BTC1 and second BCT1.Hence an array with only integers.We consider it from seventh column from right to left.Columns changed into rows give different possibilities for Catalan numbers A000108 or A000108(n+1). Among them,ECT(n) in A176239. Odd triangle is 1, 1,0,-1, 0,1,-1,0,2, 0,0,1,-2,2,0,-5, 0,0,0,1,-3,5,-5,0,14, .
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