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 1-10 of 20 results. Next

A181897 Triangle of refined rencontres numbers: T(n,k) is the number of permutations of n elements with cycle type k (k-th integer partition, defined by A194602).

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 1, 6, 8, 3, 6, 1, 10, 20, 15, 30, 20, 24, 1, 15, 40, 45, 90, 120, 144, 15, 90, 40, 120, 1, 21, 70, 105, 210, 420, 504, 105, 630, 280, 840, 210, 504, 420, 720, 1, 28, 112, 210, 420, 1120, 1344, 420, 2520, 1120, 3360, 1680, 4032
Offset: 1

Views

Author

Tilman Piesk, Mar 31 2012

Keywords

Comments

T(n,k) tells how often k appears among the first n! entries of A198380, i.e., how many permutations of n elements have the cycle type denoted by k.
This triangle is a refinement of the rencontres numbers A008290, which tell only how many permutations of n elements actually move a certain number of elements. How many of these permutations have a certain cycle type is a more detailed question, answered by this triangle.
The rows are counted from 1, the columns from 0.
Row lengths: 1, 2, 3, 5, 7, 11, ... (partition numbers A000041).
Row sums: 1, 2, 6, 24, 120, 720, ... (factorial numbers A000142).
Row maxima: 1, 1, 3, 8, 30, 144, ... (A059171).
Distinct entries per row: 1, 1, 3, 4, 6, 7, ... (A073906).
It follows from the formula given by Carlos Mafra that the rows of the triangle correspond to the coefficients of the modified Bell polynomials. - Sela Fried, Dec 08 2021
For k>0, the k-th column of triangle T(n,k) is a scaled copy of binomial coefficients binomial(n,q) where q is the least value for which p(q) exceeds or equals k+1, with p() being the integer partitions counting function, A000041(q). E.g., for column 4, the relevant binomial coefficients have q=4 as p(4)=5; for column 5, we have q=5 as p(5)>6; for column 6, we have q=5 as p(5)=7. The scale factor for column k is given by A385081(k+1). This triangle gives coefficients for expressing the characteristic polynomial and determinant of a matrix solely in terms of traces; see extended comment, below, under "Links". - Gregory Gerard Wojnar, Jun 24 2025

Examples

			Triangle begins:
  1;
  1,  1;
  1,  3,  2;
  1,  6,  8,  3,  6;
  1, 10, 20, 15, 30,  20,  24;
  1, 15, 40, 45, 90, 120, 144, 15, 90, 40, 120;
  ...
		

Crossrefs

Cf. A036039 and references therein for different ordering of terms within each row.

Programs

  • Mathematica
    Table[CoefficientRules[ n! CycleIndex[SymmetricGroup[n], s] // Expand][[All, 2]], {n, 1, 8}] // Grid (* Geoffrey Critzer, Nov 09 2014 *)
    (* Alternative program *)
    partitionMultiplicities[aPartn_]:=Table[Count[aPartn,m],{m,Total[aPartn]}]
    partitionBase[aPartn_]:=Sum[m*aPartn[[m]],{m,Length[aPartn]}]
    partitionFactorial[aPartn_]:=Product[m^aPartn[[m]],{m,partitionBase[aPartn]}]
    partitionParts[aPartn_]:=Sum[aPartn[[m]],{m,Length[aPartn]}]
    A181897[aPartn_]:=Multinomial@@aPartn*partitionBase[aPartn]!/(partitionFactorial[aPartn]*partitionParts[aPartn]!)
    Grid[Table[Map[A181897,ReverseSort[Map[partitionMultiplicities,Partitions[n]],LexicographicOrder]],{n,2,12}]] (* Gregory Gerard Wojnar, Jun 24 2025 *)

Formula

T(n,1) = A000217(n).
T(n,2) = A007290(n).
Let m2, m3, ... count the appearances of 2, 3, ... in the cycle type. E.g., the cycle type 2, 2, 2, 3, 3, 4 implies m2=3, m3=2, m4=1. Then T(n;m2,m3,m4,...) = n!/((2^m2 3^m3 4^m4 ...) m1!m2!m3!m4! ...) where m1 = n - 2m2 - 3m3 - 4m4 - ... . - Carlos Mafra, Nov 25 2014

A249620 Triangle read by rows: T(m,n) = number of partitions of the multiset with m elements and signature corresponding to n-th integer partition (A194602).

Original entry on oeis.org

1, 1, 2, 2, 5, 4, 3, 15, 11, 7, 9, 5, 52, 36, 21, 26, 12, 16, 7, 203, 135, 74, 92, 38, 52, 19, 66, 29, 31, 11, 877, 566, 296, 371, 141, 198, 64, 249, 98, 109, 30, 137, 47, 57, 15, 4140, 2610, 1315, 1663, 592, 850, 250, 1075, 392, 444, 105, 560
Offset: 0

Views

Author

Tilman Piesk, Nov 04 2014

Keywords

Comments

This triangle shows the same numbers in each row as A129306 and A096443, but in this arrangement the multisets in column n correspond to the n-th integer partition in the infinite order defined by A194602.
Row lengths: A000041 (partition numbers), Row sums: A035310
Columns: 0: A000110 (Bell), 1: A035098 (near-Bell), 2: A169587, 4: A169588
Last in row: end-1: A091437, end: A000041 (partition numbers)
The rightmost columns form a reflected version of the triangle A126442:
n 0 1 2 4 6 10 14 21 (A000041(1,2,3...)-1)
m
1 1
2 2 2
3 5 4 3
4 15 11 7 5
5 52 36 21 12 7
6 203 135 74 38 19 11
7 877 566 296 141 64 30 15
8 4140 2610 1315 592 250 105 45 22
A249619 shows the number of permutations of the same multisets.

Examples

			See "The T(5,2)=21 partitions of {1,1,1,2,3}" link. Similar links for m=1..8 are in "Partitions of multisets" (Wikiversity).
Triangle begins:
  n     0    1   2   3   4   5   6   7   8   9  10
m
0       1
1       1
2       2    2
3       5    4   3
4      15   11   7   9   5
5      52   36  21  26  12  16   7
6     203  135  74  92  38  52  19  66  29  31  11
		

Crossrefs

A198380 Cycle type of the n-th finite permutation represented by index number of A194602.

Original entry on oeis.org

0, 1, 1, 2, 2, 1, 1, 3, 2, 4, 4, 2, 2, 4, 1, 2, 3, 4, 4, 2, 2, 1, 4, 3, 1, 3, 3, 5, 5, 3, 2, 5, 4, 6, 6, 4, 4, 6, 2, 4, 5, 6, 6, 4, 4, 2, 6, 5, 2, 5, 4, 6, 6, 4, 1, 3, 2, 4, 4, 2, 3, 5, 4, 6, 6, 5, 5, 3, 6, 4, 5, 6, 4, 6, 2, 4, 5, 6, 2, 4, 1, 2, 3, 4, 4, 6
Offset: 0

Views

Author

Tilman Piesk, Oct 23 2011

Keywords

Comments

This sequence shows the cycle type of each finite permutation (A195663) as the index number of the corresponding partition. (When a permutation has a 3-cycle and a 2-cycle, this corresponds to the partition 3+2, etc.) Partitions can be ordered, so each partition can be denoted by its index in this order, e.g. 6 for the partition 3+2. Compare A194602.
From the properties of A194602 follows:
Entries 1,2,4,6,10,14,21... ( A000041(n)-1 from n=2 ) correspond to permutations with exactly one n-cycle (and no other cycles).
Entries 1,3,7,15,30,56,101... ( A000041(2n-1) from n=1 ) correspond to permutations with exactly n 2-cycles (and no other cycles), so these are the symmetric permutations.
Entries n = 1,3,4,7,9,10,12... ( A194602(n) has an even binary digit sum ) correspond to even permutations. This goes along with the fact, that a permutation is even when its partition contains an even number of even addends.
(Compare "Table for A194602" in section LINKS. Concerning the first two properties see especially the end of this file.)

Crossrefs

Cf. A195663, A195664, A055089 (ordered finite permutations).
Cf. A194602 (ordered partitions interpreted as binary numbers).
Cf. A181897 (number of n-permutations with cycle type k).

Extensions

Changed offset to 0 by Tilman Piesk, Jan 25 2012

A211350 Refined triangle A124323: T(n,k) is the number of partitions of an n-set that are of type k (k-th integer partition, defined by A194602).

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 6, 4, 3, 1, 1, 10, 10, 15, 5, 10, 1, 1, 15, 20, 45, 15, 60, 6, 15, 15, 10, 1, 1, 21, 35, 105, 35, 210, 21, 105, 105, 70, 7, 105, 21, 35, 1, 1, 28, 56, 210, 70, 560, 56, 420, 420, 280, 28, 840, 168, 280, 8, 105, 210, 280, 28
Offset: 1

Views

Author

Tilman Piesk, Apr 09 2012

Keywords

Comments

Name could also be "Triangle of multinomial coefficients, read by rows (version 4)", compare A036040, A080575, A178867. The latter and this one differ only in the order of columns.
The rows are counted from 1, the columns from 0.
Row lengths: 1,2,3,5,7,11... (partition numbers A000041)
Row sums: 1,2,5,15,52,203... (Bell numbers A000110)
Row maxima: 1,1,3,6,15,60,210,840,3780,12600,69300,415800... (A102356)
Distinct entries per row: 1,1,2,4,4,7,7,13,17,23,26,40... (A102465)
Rightmost columns are those from Pascal's triangle A007318 without the second one (i.e. triangle A184049). The other columns - (always?) without a 1 at the top - are multiples of these columns from Pascal's triangle; so actually only the top elements of each column are needed to calculate the other entries; these top elements are in A211360. (The top elements of the related triangle A178867 are in A178866.)

Crossrefs

A211351 Refined triangle A091867: T(n,k) is the number of noncrossing partitions of an n-set that are of type k (k-th integer partition, defined by A194602).

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 6, 4, 2, 1, 1, 10, 10, 10, 5, 5, 1, 1, 15, 20, 30, 15, 30, 6, 5, 6, 3, 1, 1, 21, 35, 70, 35, 105, 21, 35, 42, 21, 7, 21, 7, 7, 1, 1, 28, 56, 140, 70, 280, 56, 140, 168, 84, 28, 168, 56, 56, 8, 14, 28, 28, 8, 8, 4, 1
Offset: 1

Views

Author

Tilman Piesk, Apr 09 2012

Keywords

Comments

The rows are counted from 1, the columns from 0.
Row lengths: 1,2,3,5,7,11... (partition numbers A000041)
Row sums: 1,2,5,14,42,132... (Catalan numbers A000108)
Row maxima: 1,1,3,6,10,30,105,280,756,2520,6930,18480 (A130760)
Distinct entries per row: 1,1,2,4,3,7,7,11,12,18,18,30
Rightmost columns are those from Pascal's triangle A007318 without the second one (i.e. triangle A184049). The other columns - (always?) without a 1 at the top - are multiples of these columns from Pascal's triangle; so actually only the top elements of each column are needed to calculate the other entries; these top elements are in A211361.

Crossrefs

A249619 Triangle T(m,n) = number of permutations of a multiset with m elements and signature corresponding to n-th integer partition (A194602).

Original entry on oeis.org

1, 1, 2, 1, 6, 3, 1, 24, 12, 4, 6, 1, 120, 60, 20, 30, 5, 10, 1, 720, 360, 120, 180, 30, 60, 6, 90, 15, 20, 1, 5040, 2520, 840, 1260, 210, 420, 42, 630, 105, 140, 7, 210, 21, 35, 1, 40320, 20160, 6720, 10080, 1680, 3360, 336, 5040, 840, 1120, 56
Offset: 0

Views

Author

Tilman Piesk, Nov 04 2014

Keywords

Comments

This triangle shows the same numbers in each row as A036038 and A078760 (the multinomial coefficients), but in this arrangement the multisets in column n correspond to the n-th integer partition in the infinite order defined by A194602.
Row lengths: A000041 (partition numbers), Row sums: A005651
Columns: 0: A000142 (factorials), 1: A001710, 2: A001715, 3: A133799, 4: A001720, 6: A001725, 10: A001730, 14: A049388
Last in row: end-2: A037955 after 1 term mismatch, end-1: A001405, end: A000012
The rightmost columns form the triangle A173333:
n 0 1 2 4 6 10 14 21 (A000041(1,2,3...)-1)
m
1 1
2 2 1
3 6 3 1
4 24 12 4 1
5 120 60 20 5 1
6 720 360 120 30 6 1
7 5040 2520 840 210 42 7 1
8 40320 20160 6720 1680 336 56 8 1
A249620 shows the number of partitions of the same multisets. A187783 shows the number of permutations of special multisets.

Examples

			Triangle begins:
  n     0    1    2    3   4   5  6   7   8   9 10
m
0       1
1       1
2       2    1
3       6    3    1
4      24   12    4    6   1
5     120   60   20   30   5  10  1
6     720  360  120  180  30  60  6  90  15  20  1
		

Crossrefs

A211352 Refined triangle A211356: T(n,k) is the number of partitions up to rotation of an n-set that are of type k (k-th integer partition, defined by A194602).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 2, 2, 3, 1, 2, 1, 1, 3, 4, 9, 3, 10, 1, 5, 3, 3, 1, 1, 3, 5, 15, 5, 30, 3, 15, 15, 10, 1, 15, 3, 5, 1, 1, 4, 7, 29, 10, 70, 7, 56, 54, 37, 4, 105, 21, 35, 1, 18, 29, 37, 4, 7, 7, 1
Offset: 1

Views

Author

Tilman Piesk, Apr 09 2012

Keywords

Comments

The rows are counted from 1, the columns from 0.
Row lengths: 1,2,3,5,7,11... (partition numbers A000041)
Row sums: 1,2,3,7,12,43... (A084423)
Row maxima: 1,1,1,2,3,10,30,105,420,1268,6300...
Distinct entries per row: 1,1,1,2,3,6,6,13,17,25,25...
Rightmost columns are those from the triangle of circular binomial coefficients A047996 without the second column (i.e.triangle A037306).

Crossrefs

A211353 Refined triangle A211357: T(n,k) is the number of noncrossing partitions up to rotation of an n-set that are of type k (k-th integer partition, defined by A194602).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 3, 4, 6, 3, 5, 1, 2, 1, 1, 1, 1, 3, 5, 10, 5, 15, 3, 5, 6, 3, 1, 3, 1, 1, 1, 1, 4, 7, 19, 10, 35, 7, 19, 21, 12, 4, 21, 7, 7, 1, 3, 4, 4, 1, 1, 1, 1, 1, 4, 10, 28, 14, 70, 14, 48, 56, 28, 10
Offset: 1

Views

Author

Tilman Piesk, Apr 09 2012

Keywords

Comments

The rows are counted from 1, the columns from 0.
Row lengths: 1,2,3,5,7,11... (partition numbers A000041)
Row sums: 1,2,3,6,10,28... (A054357)
Row maxima: 1,1,1,2,2,6,15,35,84,252,630,1542...
Distinct entries per row: 1,1,1,2,2,6,6,9,11,17,17,30...
Rightmost columns are those from the triangle of circular binomial coefficients A047996 without the second column (i.e.triangle A037306).

Crossrefs

A211354 Refined triangle A211358: T(n,k) is the number of partitions up to rotation and reflection of an n-set that are of type k (k-th integer partition, defined by A194602).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 2, 2, 3, 1, 2, 1, 1, 3, 3, 8, 3, 6, 1, 5, 3, 3, 1, 1, 3, 4, 12, 4, 18, 3, 11, 9, 7, 1, 12, 3, 4, 1, 1, 4, 5, 22, 8, 38, 5, 39, 33, 25, 4, 57, 12, 19, 1, 17, 22, 25, 4, 5, 7, 1, 1, 4, 7, 30, 10, 76, 10, 85, 76, 55
Offset: 1

Views

Author

Tilman Piesk, Apr 09 2012

Keywords

Comments

The rows are counted from 1, the columns from 0.
Row lengths: 1,2,3,5,7,11... (partition numbers A000041)
Row sums: 1,2,3,7,12,37... (A084708)
Row maxima: 1,1,1,2,3,8,18,57,228,668,3220
Distinct entries per row: 1,1,1,2,3,5,8,14,17,26,30
Rightmost columns are those from the triangle A052307 without the second column.

Crossrefs

A211355 Refined triangle A211359: T(n,k) is the number of noncrossing partitions up to rotation and reflection of an n-set that are of type k (k-th integer partition, defined by A194602).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 3, 3, 5, 3, 3, 1, 2, 1, 1, 1, 1, 3, 4, 8, 4, 9, 3, 4, 4, 2, 1, 3, 1, 1, 1, 1, 4, 5, 14, 8, 19, 5, 14, 13, 8, 4, 12, 4, 4, 1, 3, 4, 3, 1, 1, 1, 1, 1, 4, 7, 20, 10, 38, 10, 30, 32, 16, 7, 48
Offset: 1

Views

Author

Tilman Piesk, Apr 09 2012

Keywords

Comments

The rows are counted from 1, the columns from 0.
Row lengths: 1,2,3,5,7,11... (partition numbers A000041)
Row sums: 1,2,3,6,10,24... (A111275)
Row maxima: 1,1,1,2,2,5,9,19,48,132,330,781
Distinct entries per row: 1,1,1,2,2,4,6,9,15,21,28,43
Rightmost columns are those from the triangle A052307 without the second column.

Crossrefs

Showing 1-10 of 20 results. Next