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.

A118980 Triangle read by rows: rows = inverse binomial transforms of columns of A309220.

Original entry on oeis.org

1, 2, 1, 6, 5, 2, 14, 22, 18, 6, 34, 85, 118, 84, 24, 82, 311, 660, 780, 480, 120, 198, 1100, 3380, 5964, 6024, 3240, 720, 478, 3809, 16380, 40740, 60480, 52920, 25200, 5040, 1154, 13005, 76518, 258804, 531864, 676080, 519840, 221760, 40320, 2786, 43978, 348462, 1564314, 4286880, 7444800, 8240400
Offset: 1

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Author

Gary W. Adamson, May 07 2006

Keywords

Comments

First few columns of A309220:
1, 2, 6, 14, 34, ...
1, 3, 11, 36, 119, ...
1, 4, 18, 76, 322, ...
1, 5, 27, 140, 727, ...
1, 6, 38, 234, 1442, ...
1, 7, 51, 364, 2599, ...
1, 8, 66, 536, 4354, ...
...

Examples

			First few rows of the triangle:
   1;
   2,   1;
   6,   5,   2;
  14,  22,  18,   6;
  34,  85, 118,  84,  24;
  82, 311, 660, 780, 480, 120;
  ...
Column 3 of A309220 = (6, 11, 18, 27, 38, 51, ...), whose inverse binomial transform is (6, 5, 2).
		

Crossrefs

The leading column is A099425, and the rightmost two diagonals are A038720 and A000142.

Programs

  • Maple
    with(transforms);
    M := 12;
    T := [1];
    S := series((1 + x^2)/(1-x-x^2 + x*y), x, 120):
    for n from 1 to M do
    R2 := expand(coeff(S, x, n));
    R3 := [seq(abs(coeff(R2,y,n-i)),i=0..n)];
    f := k-> add( R3[i]*k^(n-i+1), i=1..nops(R3) ):
    s1 := [seq(f(i),i=1..3*n)];
    s2 := BINOMIALi(s1);
    s3 := [seq(s2[i],i=1..n+1)];
    T := [op(T), op(s3)];
    od:
    T;  # N. J. A. Sloane, Aug 12 2019

Extensions

Edited and extended by N. J. A. Sloane, Aug 12 2019, guided by the comments of R. J. Mathar from Oct 30 2011