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 1-7 of 7 results.

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

A182700 Triangle T(n,k) = n*A000041(n-k), 0<=k<=n, read by rows.

Original entry on oeis.org

0, 1, 1, 4, 2, 2, 9, 6, 3, 3, 20, 12, 8, 4, 4, 35, 25, 15, 10, 5, 5, 66, 42, 30, 18, 12, 6, 6, 105, 77, 49, 35, 21, 14, 7, 7, 176, 120, 88, 56, 40, 24, 16, 8, 8, 270, 198, 135, 99, 63, 45, 27, 18, 9, 9, 420, 300, 220, 150, 110, 70, 50, 30, 20, 10, 10, 616, 462, 330, 242, 165, 121, 77, 55, 33
Offset: 0

Views

Author

Omar E. Pol, Nov 27 2010

Keywords

Comments

T(n,k) is the sum of the parts of all partitions of n that contain k as a part, assuming that all partitions of n have 0 as a part: Thus, column 0 gives the sum of the parts of all partitions of n.
By definition all entries in row n>0 are divisible by n.
Row sums are 0, 2, 8, 21, 48, 95, 180, 315, 536, 873, 1390, 2145,...
The partitions of n+k that contain k as a part can be obtained by adding k to every partition of n assuming that all partitions of n have 0 as a part.
For example, the partitions of 6+k that contain k as a part are
k + 6
k + 3 + 3
k + 4 + 2
k + 2 + 2 + 2
k + 5 + 1
k + 3 + 2 + 1
k + 4 + 1 + 1
k + 2 + 2 + 1 + 1
k + 3 + 1 + 1 + 1
k + 2 + 1 + 1 + 1 + 1
k + 1 + 1 + 1 + 1 + 1 + 1
The partition number A000041(n) is also the number of partitions of m*(n+k) into parts divisible by m and that contain m*k as a part, with k>=0, m>=1, n>=0 and assuming that all partitions of n have 0 as a part.

Examples

			For n=7 and k=4 there are 3 partitions of 7 that contain 4 as a part. These partitions are (4+3)=7, (4+2+1)=7 and (4+1+1+1)=7. The sum is 7+7+7 = 7*3 = 21. By other way, the partition number of 7-4 is A000041(3) = p(3)=3, then 7*3 = 21, so T(7,4) = 21.
Triangle begins with row n=0 and columns 0<=k<=n :
0,
1, 1,
4, 2, 2,
9, 6, 3, 3,
20,12,8, 4, 4,
35,25,15,10,5, 5,
66,42,30,18,12,6, 6
		

Crossrefs

Two triangles that are essentially the same as this are A027293 and A140207. - N. J. A. Sloane, Nov 28 2010
Row sums give A182704.

Programs

  • Maple
    A182700 := proc(n,k) n*combinat[numbpart](n-k) ; end proc:
    seq(seq(A182700(n,k),k=0..n),n=0..15) ;
  • Mathematica
    Table[n*PartitionsP[n-k], {n, 0, 11}, {k, 0, n}] // Flatten (* Robert Price, Jun 23 2020 *)
  • PARI
    A182700(n,k) = n*numbpart(n-k)

Formula

T(n,0) = A066186(n).
T(n,k) = A182701(n,k), n>=1 and k>=1.
T(n,n) = n = min { T(n,k); 0<=k<=n }.

A182702 Triangle T(n,k) = n*(A000041(n-k)) read by rows, k>=0.

Original entry on oeis.org

1, 4, 2, 9, 6, 3, 20, 12, 8, 4, 35, 25, 15, 10, 5, 66, 42, 30, 18, 12, 6, 105, 77, 49, 35, 21, 14, 7, 176, 120, 88, 56, 40, 24, 16, 8, 270, 198, 135, 99, 63, 45, 27, 18, 9, 420, 300, 220, 150, 110, 70, 50, 30, 20, 10, 616, 462, 330, 242, 165, 121, 77, 55, 33, 22, 11
Offset: 1

Views

Author

Omar E. Pol, Nov 28 2010

Keywords

Comments

The same as A182700, but without the last term of row n.

Examples

			Triangle begins:
1;
4, 2;
9, 6, 3;
20, 12, 8, 4;
35, 25, 15, 10, 5;
66, 42, 30, 18, 12, 6;
		

Crossrefs

Column 1 give A066186.

Programs

  • Mathematica
    Table[n*PartitionsP[n-k], {n, 0, 11}, {k, 0,  n - 1}] // Flatten (* Robert Price, Jun 23 2020 *)
  • PARI
    tabl(nn) = {for (n = 1, nn, for (k = 0, n-1, print1(n*numbpart(n-k), ", ");); print(););} \\ Michel Marcus, Feb 13 2014

Extensions

More terms from Michel Marcus, Feb 13 2014

A182704 Row sums of triangle A182700.

Original entry on oeis.org

0, 2, 8, 21, 48, 95, 180, 315, 536, 873, 1390, 2145, 3264, 4849, 7112, 10260, 14640, 20604, 28746, 39653, 54280, 73626, 99176, 132549, 176112, 232400, 305032, 398034, 516880, 667725, 858870
Offset: 0

Views

Author

Omar E. Pol, Nov 28 2010

Keywords

Crossrefs

Programs

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

Formula

a(n) = n*A000070(n).
G.f.: x*f'(x), where f(x) = (1/(1 - x))*Product_{k>=1} 1/(1 - x^k). - Ilya Gutkovskiy, Apr 13 2017

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).

A228816 Sum of all parts of all partitions of n that contain 1 as a part.

Original entry on oeis.org

1, 2, 6, 12, 25, 42, 77, 120, 198, 300, 462, 672, 1001, 1414, 2025, 2816, 3927, 5346, 7315, 9800, 13167, 17424, 23046, 30120, 39375, 50908, 65772, 84280, 107822, 136950, 173724, 218944, 275517, 344862, 430850, 535788, 665149, 822206, 1014585, 1247400
Offset: 1

Views

Author

Omar E. Pol, Sep 23 2013

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Total[Flatten[Select[IntegerPartitions[n],MemberQ[#,1]&]]],{n,40}] (* Harvey P. Dale, Sep 27 2015 *)

Formula

a(n) = n*A000041(n-1).
a(n) = A066186(n-1) + A000041(n-1), n >= 2.
a(n) = A194552(n-1) + A000070(n-1), n >= 2.

A228823 Triangle read by rows: T(n,k) = total number of parts in all partitions of n that contain k as a part, n>=1, 1<=k<=n.

Original entry on oeis.org

1, 2, 1, 5, 2, 1, 9, 5, 2, 1, 17, 9, 5, 2, 1, 27, 17, 9, 5, 2, 1, 46, 27, 17, 9, 5, 2, 1, 69, 46, 27, 17, 9, 5, 2, 1, 108, 69, 46, 27, 17, 9, 5, 2, 1, 158, 108, 69, 46, 27, 17, 9, 5, 2, 1, 234, 158, 108, 69, 46, 27, 17, 9, 5, 2, 1, 331, 234, 158, 108, 69
Offset: 1

Views

Author

Omar E. Pol, Sep 25 2013

Keywords

Comments

Row n lists the first n elements of A093694 in decreasing order.

Examples

			Triangle begins:
1;
2,     1;
5,     2,   1;
9,     5,   2,   1;
17,    9,   5,   2,  1;
27,   17,   9,   5,  2,  1;
46,   27,  17,   9,  5,  2,  1;
69,   46,  27,  17,  9,  5,  2,  1;
108,  69,  46,  27, 17,  9,  5,  2,  1;
158, 108,  69,  46, 27, 17,  9,  5,  2,  1;
234, 158, 108,  69, 46, 27, 17,  9,  5,  2,  1;
331, 234, 158, 108, 69, 46, 27, 17,  9,  5,  2,  1;
		

Crossrefs

Formula

T(n,k) = A000041(n-k) + A006128(n-k) = A093694(n-k).
Showing 1-7 of 7 results.