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.

A134479 Row sums of triangle A134478.

Original entry on oeis.org

1, 3, 9, 18, 30, 45, 63, 84, 108, 135, 165, 198, 234, 273, 315, 360, 408, 459, 513, 570, 630, 693, 759, 828, 900, 975, 1053, 1134, 1218, 1305, 1395, 1488, 1584, 1683, 1785, 1890, 1998, 2109, 2223, 2340, 2460, 2583, 2709, 2838, 2970, 3105, 3243, 3384, 3528, 3675, 3825
Offset: 0

Views

Author

Gary W. Adamson, Oct 27 2007

Keywords

Comments

Essentially the same as A045943. - R. J. Mathar, Mar 28 2012

Examples

			a(3) = 18 = (1, 3, 3, 1) dot (1, 2, 4, -1) = (1 + 6 + 12 -1).
a(3) = 18 = sum of row 3 terms of triangle A134478: (3 = 4 + 5 + 6).
		

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[Sum[n + k, {k, 0, n}], {n, 1, 50}]] (* G. C. Greubel, Sep 24 2017 *)
  • PARI
    concat([1], for(n=1,50, print1(sum(k=0,n, n+k), ", "))) \\ G. C. Greubel, Sep 24 2017
    
  • PARI
    Vec((1 + 3*x^2 - x^3) / (1 - x)^3 + O(x^60)) \\ Colin Barker, Sep 25 2017

Formula

Binomial transform of [1, 2, 4, -1, 1, -1, 1, ...].
From Colin Barker, Sep 24 2017: (Start)
G.f.: (1 + 3*x^2 - x^3) / (1 - x)^3.
a(n) = 3*n*(1 + n) / 2 for n>0.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>3. (End)

Extensions

Terms a(14) onward added by G. C. Greubel, Sep 24 2017

A134480 A134478 * A000012.

Original entry on oeis.org

1, 3, 2, 9, 7, 4, 18, 15, 11, 6, 30, 26, 21, 15, 8, 45, 40, 34, 27, 19, 10, 63, 57, 50, 42, 33, 23, 12, 84, 77, 69, 60, 50, 39, 27, 14, 108, 100, 91, 81, 70, 58, 45, 31, 16, 135, 126, 116, 105, 93, 80, 66, 51, 35, 18
Offset: 0

Views

Author

Gary W. Adamson, Oct 27 2007

Keywords

Comments

Row sums = A134481: (1, 5, 20, 50, 100, 175, ...).
Left border = A134479.

Examples

			First few rows of the triangle:
   1;
   3,  2;
   9,  7,  4;
  18, 15, 11,  6;
  30, 26, 21, 15,  8;
  45, 40, 34, 27, 19, 10;
  63, 57, 50, 42, 33, 23, 12;
  ...
		

Crossrefs

Formula

A134478 * A000012 as infinite lower triangular matrices. Triangle read by rows, partial sums of A134478 terms starting from the right.
Showing 1-2 of 2 results.