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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A316140 Denominator of the autosequence 2/((n+2)*(n+3)) difference table written by antidiagonals.

Original entry on oeis.org

3, 6, 6, 10, 15, 10, 15, 30, 30, 15, 21, 105, 70, 105, 21, 28, 84, 140, 140, 84, 28, 36, 126, 252, 315, 252, 126, 36, 45, 180, 420, 630, 630, 420, 180, 45, 55, 495, 660, 1155, 1386, 1155, 660, 495, 55, 66, 330
Offset: 0

Views

Author

Paul Curtz, Jun 25 2018

Keywords

Examples

			Difference table:
   1/3,   1/6,    1/10,   1/15,  ...
  -1/6,  -1/15,  -1/30,  -2/105, ...
   1/10,  1/30,   1/70,   1/140, ...
  -1/15, -2/105, -1/140, -1/315, ... .
  ...
Table starts:
   3   6   10    15    21    28   ...
   6  15   30   105    84   126   ...
  10  30   70   140   252   420   ...
  15 105  140   315   630  1155   ...
  21  84  252   630  1386  2772   ...
  ...
As a triangle:
   3;
   6,  6;
  10, 15, 10;
  15, 30, 30, 15;
  ...
		

Crossrefs

Cf. A000217, A003506, A033876? (main diagonal), A059481, A109613.

Programs

  • PARI
    tabl(nn) = {nn = 2*nn; m = matrix(nn, nn, n, k, if (n==1, 2/((k+1)*(k+2)))); for (n=2, nn, for (k=1, nn-n +1, m[n, k] = m[n-1, k+1] - m[n-1,k];);); nn = nn/2; matrix(nn, nn, n, k, denominator(m[n,k]));} \\ Michel Marcus, Jul 05 2018

A327809 Regular triangle, coefficients of the polynomial P(n)(x) = (-1)^(n+1)*(2*n+1)*binomial(2*n, n)*Sum_{i=0..n} x^i*binomial(n, i)/(n+i+1).

Original entry on oeis.org

-1, 3, 2, -10, -15, -6, 35, 84, 70, 20, -126, -420, -540, -315, -70, 462, 1980, 3465, 3080, 1386, 252, -1716, -9009, -20020, -24024, -16380, -6006, -924, 6435, 40040, 108108, 163800, 150150, 83160, 25740, 3432, -24310, -175032, -556920, -1021020, -1178100, -875160, -408408, -109395, -12870
Offset: 0

Views

Author

Michel Marcus, Sep 26 2019

Keywords

Examples

			Triangle begins:
     -1;
      3,     2;
    -10,   -15,     -6;
     35,    84,     70,     20;
   -126,  -420,   -540,   -315,   -70;
    462,  1980,   3465,   3080,   1386,   252;
  -1716, -9009, -20020, -24024, -16380, -6006, -924;
  ...
		

Crossrefs

Cf. A046899 (Q(x) polynomials, up to sign).
Cf. A001700 (1st column, up to sign), A033876 (right diagonal, up to sign).

Programs

  • PARI
    pol(n) = (-1)^(n+1)*(2*n+1)*binomial(2*n, n)*sum(i=0, n, x^i*binomial(n, i)/(n+i+1));
    row(n) = Vecrev(pol(n));
    tabl(nn) = for (n=0, nn, print(row(n)));
Previous Showing 11-12 of 12 results.