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.

A182706 Row sums of triangle A182702.

Original entry on oeis.org

1, 6, 18, 44, 90, 174, 308, 528, 864, 1380, 2134, 3252, 4836, 7098, 10245, 14624, 20587, 28728, 39634, 54260, 73605, 99154, 132526, 176088, 232375, 305006, 398007, 516852, 667696, 858840
Offset: 1

Views

Author

Omar E. Pol, Nov 28 2010

Keywords

Crossrefs

Programs

  • Mathematica
    Total /@ Table[n*PartitionsP[n-k], {n, 30}, {k, 0, n - 1}] // Flatten (* Robert Price, Jun 23 2020 *)

Formula

a(n) = n * A026905(n).

A182701 Triangle T(n,k) = n*A000041(n-k) read by rows, 1 <= k <= n. Sum of the parts of all partitions of n that contain k as a part.

Original entry on oeis.org

1, 2, 2, 6, 3, 3, 12, 8, 4, 4, 25, 15, 10, 5, 5, 42, 30, 18, 12, 6, 6, 77, 49, 35, 21, 14, 7, 7, 120, 88, 56, 40, 24, 16, 8, 8, 198, 135, 99, 63, 45, 27, 18, 9, 9, 300, 220, 150, 110, 70, 50, 30, 20, 10, 10, 462, 330, 242, 165, 121, 77, 55, 33, 22, 11, 11, 672, 504, 360, 264, 180, 132, 84, 60, 36, 24, 12, 12
Offset: 1

Views

Author

Omar E. Pol, Nov 27 2010

Keywords

Comments

By definition, the entries in row n are divisible by n.
Row sums are 1, 4, 12, 28, 60, 114, ... = n*A000070(n).
Column 1 is A228816. - Omar E. Pol, Sep 25 2013

Examples

			Triangle begins:
    1;
    2,   2;
    6,   3,   3;
   12,   8,   4,   4;
   25,  15,  10,   5,   5;
   42,  30,  18,  12,   6,   6;
   77,  49,  35,  21,  14,   7,   7;
  120,  88,  56,  40,  24,  16,   8,   8;
  198, 135,  99,  63,  45,  27,  18,   9,   9;
  300, 220, 150, 110,  70,  50,  30,  20,  10,  10;
		

Crossrefs

Programs

  • Maple
    A182701 := proc(n,k) n*combinat[numbpart](n-k) ; end proc:
    seq(seq(A182701(n,k),k=1..n),n=1..13) ; # R. J. Mathar, Nov 28 2010
  • Mathematica
    T[n_, k_] := n PartitionsP[n - k];
    Table[T[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, Dec 19 2019 *)

Formula

T(n,k) = A182700(n,k), 1 <= k < n.
T(n,k) = n*A027293(n,k). - Omar E. Pol, Sep 25 2013

A182705 Row sums of triangle A182701.

Original entry on oeis.org

1, 4, 12, 28, 60, 114, 210, 360, 603, 970, 1529, 2340, 3536, 5222, 7620, 10944, 15555, 21816, 30343, 41740, 56994, 77132, 103684, 138312, 183450, 241696, 316764, 412776, 535340, 690750, 887499, 1135072, 1446060, 1834742, 2319555, 2921616, 3667921, 4589260
Offset: 1

Views

Author

Omar E. Pol, Nov 28 2010

Keywords

Crossrefs

Programs

  • Mathematica
    Total /@ Table[n*PartitionsP[n-k], {n, 38}, {k, n}] // Flatten (* Robert Price, Jun 23 2020 *)
  • PARI
    a000070(n) = sum(k=0, n, numbpart(k));
    for(n=1, 100, print1(n*a000070(n - 1), ", ")) \\ Indranil Ghosh, Jun 08 2017
    
  • Python
    from sympy import npartitions as p
    def a000070(n): return sum([p(k) for k in range(n + 1)])
    def a(n): return n*a000070(n - 1) # Indranil Ghosh, Jun 08 2017

Formula

a(n) = n * A000070(n-1).
G.f.: x*f'(x), where f(x) = (x/(1 - x))*Product_{k>=1} 1/(1 - x^k). - Ilya Gutkovskiy, Jun 08 2017
Showing 1-3 of 3 results.