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 1-3 of 3 results.

A208658 Row sums of A208657.

Original entry on oeis.org

0, 4, 17, 52, 139, 346, 825, 1912, 4343, 9718, 21493, 47092, 102387, 221170, 475121, 1015792, 2162671, 4587502, 9699309, 20447212, 42991595, 90177514, 188743657, 394264552, 822083559, 1711276006, 3556769765, 7381975012
Offset: 1

Views

Author

Clark Kimberling, Mar 01 2012

Keywords

Crossrefs

Cf. A208657.

Programs

  • Mathematica
    f[n_, k_] := n*Binomial[n, k] - Binomial[n - 1, k - 1]
    Table[Sum[f[n, k], {k, 1, n}], {n, 1, 3 z}](* A208658 *)

Formula

Conjectures from Colin Barker, Mar 20 2012: (Start)
a(n) = -2^(-1+n)+(-1+2^n)*n.
G.f.: x^2*(4-7*x+2*x^2)/((1-x)^2*(1-2*x)^2). (End)
From Stefano Spezia, Nov 19 2023: (Start)
The above conjectures are true.
E.g.f.: exp(x)*(exp(x)*(4*x - 1) - 2*x)/2. (End)

A257055 a(n) = n*(n + 1)*(n^2 - n + 3)/6.

Original entry on oeis.org

0, 1, 5, 18, 50, 115, 231, 420, 708, 1125, 1705, 2486, 3510, 4823, 6475, 8520, 11016, 14025, 17613, 21850, 26810, 32571, 39215, 46828, 55500, 65325, 76401, 88830, 102718, 118175, 135315, 154256, 175120, 198033, 223125, 250530, 280386, 312835, 348023, 386100
Offset: 0

Views

Author

Bruno Berselli, Apr 15 2015

Keywords

Comments

Partial sums of A037235.
After 0, this sequence is the 2nd diagonal of the square array in A080851.
For n > 2, a(n)-n is the 4th column of the triangular array in A208657.

Crossrefs

Cf. similar sequences listed in A256859.

Programs

  • Magma
    [n*(n+1)*(n^2-n+3)/6: n in [0..40]];
    
  • Mathematica
    Table[n (n + 1) (n^2 - n + 3)/6, {n, 40}]
  • PARI
    vector(40, n, n--; n*(n+1)*(n^2-n+3)/6)
    
  • Sage
    [n*(n+1)*(n^2-n+3)/6 for n in (0..40)]

Formula

G.f.: x*(1 + 3*x^2)/(1 - x)^5.
a(n) = 3*A000332(n+1) + A000332(n+3).
a(n) = 5*a(n-1)-10*a(n-2)+10*a(n-3)-5*a(n-4)+a(n-5). - Wesley Ivan Hurt, May 27 2021

A208656 Triangle T(n, k) = n*C(n,k) - C(n-1,k-1), 1 <= k <= n, read by rows.

Original entry on oeis.org

0, 3, 1, 8, 7, 2, 15, 21, 13, 3, 24, 46, 44, 21, 4, 35, 85, 110, 80, 31, 5, 48, 141, 230, 225, 132, 43, 6, 63, 217, 427, 525, 413, 203, 57, 7, 80, 316, 728, 1078, 1064, 700, 296, 73, 8, 99, 441, 1164, 2016, 2394, 1974, 1116, 414, 91, 9, 120, 595, 1770
Offset: 1

Views

Author

Clark Kimberling, Mar 01 2012

Keywords

Comments

Mirror of A208657.
col 1: A005563
col 2: A127736
top edge: A000027

Examples

			First five rows:
0
3....1
8....7....2
15...21...13...3
24...46...44...21...4
		

Crossrefs

Programs

  • Mathematica
    z = 12;
    f[n_, k_] := n*Binomial[n, k] - Binomial[n - 1, k - 1]
    t = Table[f[n, k], {n, 1, z}, {k, 1, n}];
    TableForm[t] (* A208656 as a triangle *)
    Flatten[t]   (* A208656 as a sequence *)
    r = Table[f[n, k], {n, 1, z}, {k, n, 1, -1}];
    TableForm[r] (* A208657 as a triangle *)
    Flatten[r]   (* A208657 as a sequence *)
    Table[Sum[f[n, k], {k, 1, n}], {n, 1, 3 z}](* A208658 *)

Extensions

Definition amended by Georg Fischer, Feb 01 2022
Showing 1-3 of 3 results.