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.

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A207383 Triangle read by rows: T(n,k) is the sum of parts of size k in the last section of the set of partitions of n.

Original entry on oeis.org

1, 1, 2, 2, 0, 3, 3, 4, 0, 4, 5, 2, 3, 0, 5, 7, 8, 6, 4, 0, 6, 11, 6, 6, 4, 5, 0, 7, 15, 16, 9, 12, 5, 6, 0, 8, 22, 14, 18, 8, 10, 6, 7, 0, 9, 30, 30, 18, 20, 15, 12, 7, 8, 0, 10, 42, 30, 30, 20, 20, 12, 14, 8, 9, 0, 11, 56, 54, 42, 40, 25, 30, 14, 16, 9, 10, 0, 12
Offset: 1

Views

Author

Omar E. Pol, Feb 24 2012

Keywords

Comments

For further properties of this triangle see also A182703.

Examples

			Triangle begins:
   1;
   1,  2;
   2,  0,  3;
   3,  4,  0,  4;
   5,  2,  3,  0,  5;
   7,  8,  6,  4,  0,  6;
  11,  6,  6,  4,  5,  0,  7;
  15, 16,  9, 12,  5,  6,  0,  8;
  22, 14, 18,  8, 10,  6,  7,  0,  9;
  30, 30, 18, 20, 15, 12,  7,  8,  0, 10;
  42, 30, 30, 20, 20, 12, 14,  8,  9,  0, 11;
  56, 54, 42, 40, 25, 30, 14, 16,  9, 10,  0, 12;
...
From _Omar E. Pol_, Nov 28 2020: (Start)
Illustration of three arrangements of the last section of the set of partitions of 7, or more generally the 7th section of the set of partitions of any integer >= 7:
.                                        _ _ _ _ _ _ _
.     (7)                    (7)        |_ _ _ _      |
.     (4+3)                (4+3)        |_ _ _ _|_    |
.     (5+2)                (5+2)        |_ _ _    |   |
.     (3+2+2)            (3+2+2)        |_ _ _|_ _|_  |
.       (1)                  (1)                    | |
.         (1)                (1)                    | |
.         (1)                (1)                    | |
.           (1)              (1)                    | |
.         (1)                (1)                    | |
.           (1)              (1)                    | |
.           (1)              (1)                    | |
.             (1)            (1)                    | |
.             (1)            (1)                    | |
.               (1)          (1)                    | |
.                 (1)        (1)                    |_|
.    ----------------
.     19,8,5,3,2,1,1 --> Row 7 of triangle A207031
.      |/|/|/|/|/|/|
.     11,3,2,1,1,0,1 --> Row 7 of triangle A182703
.      * * * * * * *
.      1,2,3,4,5,6,7 --> Row 7 of triangle A002260
.      = = = = = = =
.     11,6,6,4,5,0,7 --> Row 7 of this triangle
.
Note that the "head" of the last section is formed by the partitions of 7 that do not contain 1 as a part. The "tail" is formed by A000041(7-1) parts of size 1. The number of rows (or zones) is A000041(7) = 15. The last section of the set of partitions of 7 contains eleven 1's, three 2's, two 3's, one 4, one 5, there are no 6's and it contains one 7. So the 7th row of triangle is [11, 6, 6, 4, 5, 0, 7]. (End)
		

Crossrefs

Column 1 is A000041.
Leading diagonal gives A000027.
Second diagonal gives A000007.
Row sums give A138879.

Formula

T(n,k) = k*A182703(n,k).

A182982 Triangle read by rows: row n lists the parts of the n-th shell of the table A182742.

Original entry on oeis.org

2, 2, 4, 2, 2, 3, 3, 6, 2, 2, 2, 2, 3, 5, 4, 4, 8, 2, 2, 2, 2, 2, 2, 2, 3, 3, 4, 3, 7, 4, 6, 5, 5, 10, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 6, 3, 4, 5, 3, 9, 4, 4, 4, 4, 8, 5, 7, 6, 6, 12, 2, 2, 2, 2, 2, 2, 2, 2, 2
Offset: 1

Views

Author

Omar E. Pol, Jan 26 2011

Keywords

Comments

Apparently this is the main table for even numbers of the shell model of partitions. It appears that the table shows an overlapping of all the heads of last sections of partitions of all even numbers. This is the table 2.0 mentioned in A135010, a geometric version of the table A182742. For odd numbers see A182983. The largest parts of the rows of the diagram give A182732.

Examples

			Triangle begins:
2,
2, 4,
2, 2, 3, 3, 6,
2, 2, 2, 2, 3, 5, 4, 4, 8,
2, 2, 2, 2, 2, 2, 2, 3, 3, 4, 3, 7, 4, 6, 5, 5, 10
		

Crossrefs

A182983 Triangle read by rows: row n lists the parts of the n-th shell of the table A182743.

Original entry on oeis.org

3, 2, 5, 2, 2, 3, 4, 7, 2, 2, 2, 2, 3, 3, 3, 3, 6, 4, 5, 9, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 5, 3, 4, 4, 3, 8, 4, 7, 5, 6, 11, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 4, 3, 3, 7, 3, 4, 6, 3, 5, 5, 3, 10, 4, 4, 5, 4, 9, 5, 8, 6, 7, 13, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2
Offset: 1

Views

Author

Omar E. Pol, Jan 26 2011

Keywords

Comments

Apparently this is the main table for odd numbers of the shell model of partitions. It appears that the table shows an overlapping of all the heads of last sections of partitions of all odd numbers. This is the table 2.1 mentioned in A135010, a geometric version of the table A182743. For even numbers see A182982. The largest parts of the rows of the diagram give A182733.

Examples

			Triangle begins:
3,
2, 5,
2, 2, 3, 4, 7,
2, 2, 2, 2, 3, 3, 3, 3, 6, 4, 5, 9
		

Crossrefs

A183152 Irregular triangle read by rows in which row n lists the emergent parts of all partitions of n, or 0 if such parts do not exist.

Original entry on oeis.org

0, 0, 0, 0, 2, 3, 2, 4, 2, 3, 3, 5, 2, 4, 2, 4, 2, 3, 6, 3, 2, 2, 5, 4, 3, 5, 2, 4, 7, 3, 2, 2, 3, 6, 3, 5, 2, 4, 2, 3, 6, 3, 2, 2, 5, 4, 8, 4, 3, 2, 2, 2, 2, 4, 7, 3, 6, 5, 3, 5, 2, 4, 7, 3, 2, 2, 3, 6, 3, 5, 9, 4, 3, 3, 2, 2, 2, 2, 5, 4, 8, 4, 3, 7, 6
Offset: 0

Views

Author

Omar E. Pol, Aug 07 2011

Keywords

Comments

For the definition of "emergent part" see A182699 and also A182709.
Also [0, 0, 0, 0] followed by the positive integers of the rows that contain zeros in the triangle A193870. For another version see A193827. - Omar E. Pol, Aug 12 2011

Examples

			If written as a triangle:
0,
0,
0,
0,
2,
3,
2,4,2,3,
3,5,2,4,
2,4,2,3,6,3,2,2,5,4,
3,5,2,4,7,3,2,2,3,6,3,5,
2,4,2,3,6,3,2,2,5,4,8,4,3,2,2,2,2,4,7,3,6,5,
3,5,2,4,7,3,2,2,3,6,3,5,9,4,3,3,2,2,2,2,5,4,8,4,3,7,6
		

Crossrefs

Row n has length A182699(n). Row sums give A182709.

A182746 Bisection (even part) of number of partitions that do not contain 1 as a part A002865.

Original entry on oeis.org

1, 1, 2, 4, 7, 12, 21, 34, 55, 88, 137, 210, 320, 478, 708, 1039, 1507, 2167, 3094, 4378, 6153, 8591, 11914, 16424, 22519, 30701, 41646, 56224, 75547, 101066, 134647, 178651, 236131, 310962, 408046, 533623, 695578, 903811, 1170827, 1512301, 1947826, 2501928
Offset: 0

Views

Author

Omar E. Pol, Dec 01 2010

Keywords

Comments

a(n+1) is the number of partitions p of 2n-1 such that (number of parts of p) is a part of p, for n >=0. - Clark Kimberling, Mar 02 2014

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember;
          if n<0 then 0
        elif n=0 then 1
        elif i<2 then 0
        else b(n, i-1) +b(n-i, i)
          fi
        end:
    a:= n-> b(2*n, 2*n):
    seq(a(n), n=0..40);  # Alois P. Heinz, Dec 01 2010
  • Mathematica
    Table[Count[IntegerPartitions[2 n -1], p_ /; MemberQ[p, Length[p]]], {n, 20}]   (* Clark Kimberling, Mar 02 2014 *)
    b[n_, i_] := b[n, i] = Which[n<0, 0, n==0, 1, i<2, 0, True, b[n, i-1] + b[n-i, i]]; a[n_] := b[2*n, 2*n]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Sep 21 2015, after Alois P. Heinz *)
    a[n_] := PartitionsP[2*n] - PartitionsP[2*n - 1]; Table[a[n], {n, 0, 40}] (* George Beck, Jun 05 2017 *)
  • PARI
    a(n)=numbpart(2*n)-numbpart(2*n-1) \\ Charles R Greathouse IV, Jun 06 2017

Formula

a(n) = p(2*n) - p(2*n-1), where p is the partition function, A000041. - George Beck, Jun 05 2017 [Shifted by Georg Fischer, Jun 20 2022]

Extensions

More terms from Alois P. Heinz, Dec 01 2010

A207779 Largest part plus the number of parts of the n-th region of the section model of partitions.

Original entry on oeis.org

2, 4, 6, 3, 9, 4, 12, 3, 6, 4, 17, 4, 7, 5, 22, 3, 6, 4, 10, 6, 5, 30, 4, 7, 5, 11, 4, 8, 6, 39, 3, 6, 4, 10, 6, 5, 15, 5, 9, 7, 6, 52, 4, 7, 5, 11, 4, 8, 6, 17, 6, 5, 11, 8, 7, 67, 3, 6, 4, 10, 6, 5, 15, 5, 9, 7, 6, 22, 4, 8, 6, 13, 5, 10, 8
Offset: 1

Views

Author

Omar E. Pol, Mar 08 2012

Keywords

Comments

Also semiperimeter of the n-th region of the geometric version of the section model of partitions. Note that a(n) is easily viewable as the sum of two perpendicular segments with a shared vertex. The horizontal segment has length A141285(n) and the vertical segment has length A194446(n). The difference between these two segments gives A194447(n). See also an illustration in the Links section. For the definition of "region" see A206437.
Also triangle read by rows: T(n,k) = largest part plus the number of parts of the k-th region of the last section of the set of partitions of n.

Examples

			Written as a triangle begins:
2;
4;
6;
3, 9;
4, 12;
3, 6, 4, 17;
4, 7, 5, 22;
3, 6, 4, 10, 6, 5, 30;
4, 7, 5, 11, 4, 8, 6, 39;
3, 6, 4, 10, 6, 5, 15, 5, 9, 7, 6, 52;
		

Crossrefs

Row n has length A187219(n). Last term of row n is A133041(n). Where record occur give A000041, n >= 1.

Formula

a(n) = A141285(n) + A194446(n).

A058399 Triangle of partial row sums of partition triangle A008284.

Original entry on oeis.org

1, 2, 1, 3, 2, 1, 5, 4, 2, 1, 7, 6, 4, 2, 1, 11, 10, 7, 4, 2, 1, 15, 14, 11, 7, 4, 2, 1, 22, 21, 17, 12, 7, 4, 2, 1, 30, 29, 25, 18, 12, 7, 4, 2, 1, 42, 41, 36, 28, 19, 12, 7, 4, 2, 1, 56, 55, 50, 40, 29, 19, 12, 7, 4, 2, 1, 77, 76, 70, 58, 43, 30, 19, 12, 7, 4, 2, 1, 101, 100, 94, 80, 62
Offset: 1

Views

Author

Wolfdieter Lang, Dec 11 2000

Keywords

Comments

T(n,m) is also the number of m-th largest elements in all partitions of n. - Omar E. Pol, Feb 14 2012
It appears that reversed rows converge to A000070. - Omar E. Pol, Mar 10 2012
The row sums give A006128. - Omar E. Pol, Mar 26 2012
T(n,m) is also the number of regions traversed by the m-th column of the section model of partitions with n sections (Cf. A135010, A206437). - Omar E. Pol, Apr 20 2012

Examples

			From _Omar E. Pol_, Mar 10 2012: (Start)
Triangle begins:
   1;
   2,  1;
   3,  2,  1;
   5,  4,  2,  1;
   7,  6,  4,  2,  1;
  11, 10,  7,  4,  2,  1;
  15, 14, 11,  7,  4,  2,  1;
  22, 21, 17, 12,  7,  4,  2,  1;
  30, 29, 25, 18, 12,  7,  4,  2,  1;
  42, 41, 36, 28, 19, 12,  7,  4,  2,  1;
  56, 55, 50, 40, 29, 19, 12,  7,  4,  2,  1;
  77, 76, 70, 58, 43, 30, 19, 12,  7,  4,  2,  1;
(End)
		

Crossrefs

Columns 1-5: A000041(n), A000065(n+1), A004250(n+2), A035300(n-1), A035301(n-1), n >= 1.
Cf. A008284.

Programs

  • Maple
    b:= proc(n, k) option remember;
          `if`(n=0, 1, `if`(k<1, 0, add(b(n-j*k, k-1), j=0..n/k)))
        end:
    T:= (n, m)-> b(n,n) -b(n,m-1):
    seq (seq (T(n, m), m=1..n), n=1..15);  # Alois P. Heinz, Apr 20 2012
  • Mathematica
    t[n_, m_] := Sum[ IntegerPartitions[n, {k}] // Length, {k, m, n}]; Table[t[n, m], {n, 1, 13}, {m, 1, n}] // Flatten (* Jean-François Alcover, Jun 21 2013 *)

Formula

T(n, m) = Sum_{k=m..n} A008284(n, k).
G.f. for m-th column: Sum_{n>=1} x^(n)/Product_{k=1..n+m-1} (1 - x^k).
T(n, m) = Sum_{k=1..n} A207379(k, m). - Omar E. Pol, Apr 22 2012

A182747 Bisection (odd part) of number of partitions that do not contain 1 as a part A002865.

Original entry on oeis.org

0, 1, 2, 4, 8, 14, 24, 41, 66, 105, 165, 253, 383, 574, 847, 1238, 1794, 2573, 3660, 5170, 7245, 10087, 13959, 19196, 26252, 35717, 48342, 65121, 87331, 116600, 155038, 205343, 270928, 356169, 466610, 609237, 792906, 1028764, 1330772, 1716486, 2207851
Offset: 0

Views

Author

Omar E. Pol, Dec 01 2010

Keywords

Comments

a(n+1) = number of partitions p of 2n such that (number of parts of p) is a part of p, for n >=0. - Clark Kimberling, Mar 02 2014

Crossrefs

Programs

  • Maple
    b:= proc(n,i) option remember;
          if n<0 then 0
        elif n=0 then 1
        elif i<2 then 0
        else b(n, i-1) +b(n-i, i)
          fi
        end:
    a:= n-> b(2*n+1, 2*n+1):
    seq(a(n), n=0..40);  # Alois P. Heinz, Dec 01 2010
  • Mathematica
    f[n_] := Table[PartitionsP[2 k + 1] - PartitionsP[2 k], {k, 0, n}] (* George Beck, Aug 14 2011 *)
    (* also *)
    Table[Count[IntegerPartitions[2 n], p_ /; MemberQ[p, Length[p]]], {n, 20}] (* Clark Kimberling, Mar 02 2014 *)
    b[n_, i_] := b[n, i] = Which[n<0, 0, n == 0, 1, i<2, 0, True, b[n, i-1] + b[n-i, i]]; a[n_] := b[2*n+1, 2*n+1]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Aug 29 2016, after Alois P. Heinz *)

Formula

a(n) = p(2*n+1)-p(2*n), where p is the partition function, A000041. - George Beck, Aug 14 2011

Extensions

More terms from Alois P. Heinz, Dec 01 2010

A195820 Total number of smallest parts in all partitions of n that do not contain 1 as a part.

Original entry on oeis.org

0, 1, 1, 3, 2, 7, 5, 12, 13, 22, 22, 43, 43, 67, 81, 117, 133, 195, 223, 312, 373, 492, 584, 782, 925, 1190, 1433, 1820, 2170, 2748, 3268, 4075, 4872, 5997, 7150, 8781, 10420, 12669, 15055, 18198, 21535, 25925, 30602, 36624, 43201, 51428, 60478, 71802, 84215
Offset: 1

Views

Author

Omar E. Pol, Oct 19 2011

Keywords

Comments

Total number of smallest parts in all partitions of the head of the last section of the set of partitions of n.

Examples

			For n = 8 the seven partitions of 8 that do not contain 1 as a part are:
.  (8)
.  (4) + (4)
.   5  + (3)
.   6  + (2)
.   3  +  3  + (2)
.   4  + (2) + (2)
.  (2) + (2) + (2) + (2)
Note that in every partition the smallest parts are shown between parentheses. The total number of smallest parts is 1+2+1+1+1+2+4 = 12, so a(8) = 12.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember;
          `if`(n=0 or i<2, 0, b(n, i-1)+
           add(`if`(n=i*j, j, b(n-i*j, i-1)), j=1..n/i))
        end:
    a:= n-> b(n, n):
    seq(a(n), n=1..60); # Alois P. Heinz, Apr 09 2012
  • Mathematica
    Table[s = Select[IntegerPartitions[n], ! MemberQ[#, 1] &]; Plus @@ Table[Count[x, Min[x]], {x, s}], {n, 50}] (* T. D. Noe, Oct 19 2011 *)
    b[n_, i_] := b[n, i] = If[n==0 || i<2, 0, b[n, i-1] + Sum[If[n== i*j, j, b[n-i*j, i-1]], {j, 1, n/i}]]; a[n_] := b[n, n]; Table[a[n], {n, 1, 60}] (* Jean-François Alcover, Oct 12 2015, after Alois P. Heinz *)
  • Sage
    def A195820(n):
        return sum(list(p).count(min(p)) for p in Partitions(n,min_part=2))
    # D. S. McNeil, Oct 19 2011

Formula

a(n) = A092269(n) - A000070(n-1).
G.f.: Sum_{i>=2} x^i/(1 - x^i) * Product_{j>=i} 1/(1 - x^j). - Ilya Gutkovskiy, Apr 03 2017
a(n) ~ exp(Pi*sqrt(2*n/3)) / (8*sqrt(3)*n) * (1 - (72 + 5*Pi^2)*sqrt(6) / (144*Pi*sqrt(n))). - Vaclav Kotesovec, Jul 31 2017

Extensions

More terms from D. S. McNeil, Oct 19 2011

A207032 Triangle read by rows: T(n,k) = number of odd/even parts >= k in the last section of the set of partitions of n, if k is odd/even.

Original entry on oeis.org

1, 1, 1, 3, 0, 1, 3, 3, 0, 1, 7, 1, 2, 0, 1, 9, 6, 2, 2, 0, 1, 15, 4, 4, 1, 2, 0, 1, 19, 13, 4, 5, 1, 2, 0, 1, 32, 10, 10, 3, 4, 1, 2, 0, 1, 40, 24, 10, 9, 4, 4, 1, 2, 0, 1, 60, 23, 18, 8, 8, 3, 4, 1, 2, 0, 1, 78, 46, 22, 19, 8, 9, 3, 4, 1, 2, 0, 1
Offset: 1

Views

Author

Omar E. Pol, Feb 17 2012

Keywords

Comments

For the calculation of row n, the number of odd/even parts, etc, take the row n from the triangle A207031 and then follow the same rules of A206563.

Examples

			Triangle begins:
  1;
  1,   1;
  3,   0,  1;
  3,   3,  0,  1;
  7,   1,  2,  0, 1;
  9,   6,  2,  2, 0, 1;
  15,  4,  4,  1, 2, 0, 1;
  19, 13,  4,  5, 1, 2, 0, 1;
  32, 10, 10,  3, 4, 1, 2, 0, 1;
  40, 24, 10,  9, 4, 4, 1, 2, 0, 1;
  60, 23, 18,  8, 8, 3, 4, 1, 2, 0, 1;
  78, 46, 22, 19, 8, 9, 3, 4, 1, 2, 0, 1;
		

Crossrefs

Formula

It appears that T(n,k) = abs(Sum_{j=k..n} (-1)^j*A207031(n,j)).
It appears that A182703(n,k) = T(n,k) - T(n,k+2). - Omar E. Pol, Feb 26 2012
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