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 1-6 of 6 results.

A000258 Expansion of e.g.f. exp(exp(exp(x)-1)-1).

Original entry on oeis.org

1, 1, 3, 12, 60, 358, 2471, 19302, 167894, 1606137, 16733779, 188378402, 2276423485, 29367807524, 402577243425, 5840190914957, 89345001017415, 1436904211547895, 24227076487779802, 427187837301557598, 7859930038606521508, 150601795280158255827
Offset: 0

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Author

Keywords

Comments

Number of 3-level labeled rooted trees with n leaves. - Christian G. Bower, Aug 15 1998
Number of pairs of set partitions (d,d') of [n] such that d is finer than d'. - A. Joseph Kennedy (kennedy_2001in(AT)yahoo.co.in), Feb 05 2006
In the Comm. Algebra paper cited, I introduce a sequence of algebras called 'class partition algebras' with this sequence as dimensions. The algebras are the centralizers of wreath product in combinatorial representation theory. - A. Joseph Kennedy (kennedy_2001in(AT)yahoo.co.in), Feb 17 2008
a(n) is the number of ways to partition {1,2,...,n} and then partition each cell (block) into subcells.

Examples

			G.f. = 1 + x + 3*x^2 + 12*x^3 + 60*x^4 + 358*x^5 + 2471*x^6 + 19302*x^7 + ...
		

References

  • J. Ginsburg, Iterated exponentials, Scripta Math., 11 (1945), 340-353.
  • Ulrike Sattler, Decidable classes of formal power series with nice closure properties, Diplomarbeit im Fach Informatik, Univ. Erlangen - Nuernberg, Jul 27 1994
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 5.2.4.

Crossrefs

Row sums of (Stirling2)^2 triangle A130191.
Column k=2 of A144150.

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Exp(Exp(Exp(x)-1)-1))); [Factorial(n-1)*b[n]: n in [1..m]]; // Vincenzo Librandi, Feb 01 2020
  • Maple
    with(combinat, bell, stirling2): seq(add(stirling2(n,k)*(bell(k)), k=0..n),n=0..30);
    with(combstruct); SetSetSetL := [T, {T=Set(S), S=Set(U,card >= 1), U=Set(Z,card >=1)},labeled];
    # alternative Maple program:
    b:= proc(n, t) option remember; `if`(n=0 or t=0, 1, add(
           b(n-j, t)*b(j, t-1)*binomial(n-1, j-1), j=1..n))
        end:
    a:= n-> b(n, 2):
    seq(a(n), n=0..23);  # Alois P. Heinz, Sep 02 2021
  • Mathematica
    nn = 20; Range[0, nn]! CoefficientList[Series[Exp[Exp[Exp[x] - 1] - 1], {x, 0, nn}], x]
    a[ n_] := If[ n < 0, 0, n! SeriesCoefficient[ Exp[ Exp[ Exp[x] - 1] - 1] , {x, 0, n}]]; (* Michael Somos, Aug 15 2015 *)
    a[n_] := Sum[StirlingS2[n, k]*BellB[k], {k, 0, n}]; Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Feb 06 2016 *)
    Table[Sum[BellY[n, k, BellB[Range[n]]], {k, 0, n}], {n, 0, 20}] (* Vladimir Reshetnikov, Nov 09 2016 *)
  • Maxima
    makelist(sum(stirling2(n,k)*belln(k),k,0,n),n,0,24); /* Emanuele Munarini, Jul 04 2011 */
    

Formula

a(n) = |A039811(n, 1)| (first column of triangle).
a(n) = Sum_{k=0..n} Stirling2(n, k)*Bell(k). - Detlef Pauly (dettodet(AT)yahoo.de), Jun 06 2002
Representation as an infinite series (Dobinski-type formula), in Maple notation: a(n)=exp(exp(-1)-1)*sum(evalf(sum(p!*stirling2(k, p)*exp(-p), p=1..k))*k^n/k!, k=0..infinity), n=1, 2, ... . - Karol A. Penson, Nov 28 2003
a(n) = Sum_{k=0..n} A055896(n,k). - R. J. Mathar, Apr 15 2008
G.f.: Sum_{j>=0} Bell(j)*x^j / Product_{k=1..j} (1 - k*x). - Ilya Gutkovskiy, Apr 06 2019

A039810 Matrix square of Stirling2 triangle A008277: 2-levels set partitions of [n] into k first-level subsets.

Original entry on oeis.org

1, 2, 1, 5, 6, 1, 15, 32, 12, 1, 52, 175, 110, 20, 1, 203, 1012, 945, 280, 30, 1, 877, 6230, 8092, 3465, 595, 42, 1, 4140, 40819, 70756, 40992, 10010, 1120, 56, 1, 21147, 283944, 638423, 479976, 156072, 24570, 1932, 72, 1, 115975, 2090424, 5971350, 5660615, 2350950, 487704, 53550, 3120, 90, 1
Offset: 1

Views

Author

Christian G. Bower, Feb 15 1999

Keywords

Comments

This triangle groups certain generalized Stirling numbers of the second kind A000558, A000559, ... They can also be interpreted in terms of trees of height 3 with n leaves and constraints on the order of the root.
From Peter Bala, Jul 19 2014: (Start)
The (n,k)-th entry in this table gives the number of double partitions of the set [n] = {1,2,...,n} into k blocks. To form a double partition of [n] we first write [n] as a disjoint union X_1 U...U X_k of k nonempty subsets (blocks) X_i of [n]. Then each block X_i is further partitioned into sub-blocks to give a double partition. For instance, {1,2,4} U {3,5} is a partition of [5] into 2 blocks and {{1,4},{2}} U {{3},{5}} is a refinement of this partition to a double partition of [5] into 2 blocks (and 4 sub-blocks).
Compare the above interpretation for the (n,k)-th entry of this table with the interpretation of the (n,k)-th entry of A013609 (the square of Pascal's triangle but with the rows read in reverse order) as counting the pairs (X,Y) of subsets of [n] such that |Y| = k and X is contained in Y. (End)
Also the Bell transform of the shifted Bell numbers B(n+1) without column 0. For the definition of the Bell transform see A264428. - Peter Luschny, Jan 28 2016
T(n,k) is the number of partitions of an n-set into colored blocks, such that exactly k colors are used and the colors are introduced in increasing order. T(3,2) = 6: 1a|23b, 13a|2b, 12a|3b, 1a|2a|3b, 1a|2b|3a, 1a|2b|3b. - Alois P. Heinz, Aug 27 2019

Examples

			Triangle begins:
      k = 1    2    3    4    5          sum
  n
  1       1                                1
  2       2    1                           3
  3       5    6    1                     12
  4      15   32   12    1                60
  5      52  175  110   20    1          358
Matrix multiplication Stirling2 * Stirling2:
                  1  0  0  0
                  1  1  0  0
                  1  3  1  0
                  1  7  6  1
.
  1  0  0  0      1  0  0  0
  1  1  0  0      2  1  0  0
  1  3  1  0      5  6  1  0
  1  7  6  1     15 32 12  1
From _Peter Bala_, Jul 19 2014: (Start)
T(5,2) = 175: A 5-set can be partitioned into 2 blocks as either a union of a 3-set and a 2-set or as a union of a 4-set and a singleton set.
In the first case there are 10 ways of partitioning a 5-set into a 3-set and a 2-set. Each 3-set can be further partitioned into sub-blocks in Bell(3) = 5 ways and each 2-set can be further partitioned into sub-blocks in Bell(2) = 2 ways. So altogether we obtain 10*5*2 = 100 double partitions of this type.
In the second case, there are 5 ways of partitioning a 5-set into a 4-set and a 1-set. Each 4-set can be further partitioned in Bell(4) = 15 ways and each 1-set can be further partitioned in Bell(1) = 1 way. So altogether we obtain 5*15*1 = 75 double partitions of this type.
Hence, in total, T(5,2) = 100 + 75 = 175. (End)
		

Crossrefs

Cf. A039811, A039814, A039813 (other products of Stirling matrices).
T(n, 1) = A000110(n) (first column) (Bell numbers).
T(n, 2) = A000558(n) 2-levels set partitions with 2 first-level classes.
T(n, n-1) = A002378(n-1) = n*(n-1) = 2*C(n,2) = set-partitions into (n-2) singletons and one of the two possible set partitions of [2].
Sum is A000258(n), 2-levels set partitions.
Another version with offset 0: A130191.
Horizontal mirror triangle is A046817.
T(2n,n) gives A321712.

Programs

  • Maple
    # The function BellMatrix is defined in A264428.
    # Adds (1,0,0,0, ..) as column 0.
    BellMatrix(n -> combinat:-bell(n+1), 10); # Peter Luschny, Jan 28 2016
  • Mathematica
    Flatten[Table[Sum[StirlingS2[n,i]*StirlingS2[i,k],{i,k,n}],{n,1,10},{k,1,n}]] (* Indranil Ghosh, Feb 22 2017 *)
    rows = 10;
    t = Table[BellB[n+1], {n, 0, rows}];
    T[n_, k_] := BellY[n, k, t];
    Table[T[n, k], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 22 2018, after Peter Luschny *)
  • PARI
    T(n, k) = sum(j=0, n, stirling(n, j, 2)*stirling(j, k, 2)); \\ Seiichi Manyama, Feb 13 2022

Formula

S2 = A008277 (Stirling numbers of the second kind).
T = (S2)^2.
T(n,k) = Sum_{i=k..n} S2(n,i) * S2(i,k).
E.g.f. of k-th column: (exp(exp(x)-1)-1)^k/k!. [corrected by Seiichi Manyama, Feb 12 2022]
From Peter Bala, Jul 19 2014: (Start)
T(n,k) = Sum_{disjoint unions X_1 U...U X_k = [n]} Bell(|X_1|)*...*Bell(|X_k|), where Bell(n) = A000110(n).
Recurrence equation: T(n+1,k+1) = Sum_{j = k..n} Bell(n+1-j)*binomial(n,j)* T(j,k).
Row sums [1,3,12,60,358,...] = A000258. (End)

Extensions

Definition and interpretation edited by Olivier Gérard, Jul 31 2011

A039813 Matrix 5th power of Stirling2 triangle A008277.

Original entry on oeis.org

1, 5, 1, 35, 15, 1, 315, 215, 30, 1, 3455, 3325, 725, 50, 1, 44590, 56605, 17100, 1825, 75, 1, 660665, 1060780, 415555, 60900, 3850, 105, 1, 11035095, 21772595, 10606470, 1998605, 172550, 7210, 140, 1, 204904830, 486459105, 286281665, 66528210, 7346955, 417690, 12390, 180, 1
Offset: 1

Views

Author

Christian G. Bower, Feb 15 1999

Keywords

Examples

			Triangle begins:
      1;
      5,     1;
     35,    15,     1;
    315,   215,    30,    1;
   3455,  3325,   725,   50,  1;
  44590, 56605, 17100, 1825, 75, 1;
  ...
		

Crossrefs

Cf. A008277, A000357 (first column).

Programs

  • Mathematica
    max = 9; m = MatrixPower[Array[StirlingS2, {max, max}], 5]; Table[Take[m[[n]], n], {n, 1, max}] // Flatten (* Jean-François Alcover, Mar 03 2014 *)

Formula

E.g.f. k-th column: (( exp(exp(exp(exp(exp(x)-1)-1)-1)-1)-1 )^k)/k!. [corrected by Seiichi Manyama, Feb 12 2022]

A039815 Triangle read by rows: matrix cube of the Stirling-1 triangle A008275.

Original entry on oeis.org

1, -3, 1, 15, -9, 1, -105, 87, -18, 1, 947, -975, 285, -30, 1, -10472, 12657, -4680, 705, -45, 1, 137337, -188090, 82887, -15960, 1470, -63, 1, -2085605, 3159699, -1598954, 370237, -43890, 2730, -84, 1, 36017472, -59326371, 33613353, -9009294, 1292067, -103950, 4662, -108, 1
Offset: 1

Views

Author

Christian G. Bower, Feb 15 1999

Keywords

Examples

			Triangle begins:
       1;
      -3,     1;
      15,    -9,     1;
    -105,    87,   -18,   1;
     947,  -975,   285, -30,   1;
  -10472, 12657, -4680, 705, -45, 1;
  ...
		

Crossrefs

Cf. A000268 (first column), A008275.

Programs

  • Maple
    T:= Matrix(10,10,(i,j) -> `if`(i>= j, combinat:-stirling1(i,j),0)):
    M:= T^3:
    seq(seq(M[i,j],j=1..i),i=1..10); # Robert Israel, Sep 12 2022
  • Mathematica
    Flatten[Table[SeriesCoefficient[(Log[1+Log[1+Log[1+x]]])^k, {x,0,n}] n!/k!, {n,9}, {k,n}]] (* Stefano Spezia, Sep 12 2022 *)

Formula

E.g.f. of k-th column: ((log(1+log(1+log(1+x))))^k)/k!.

A039812 Triangle read by rows: matrix 4th power of the Stirling2 triangle A008277.

Original entry on oeis.org

1, 4, 1, 22, 12, 1, 154, 136, 24, 1, 1304, 1650, 460, 40, 1, 12915, 21904, 8550, 1160, 60, 1, 146115, 318521, 162904, 30590, 2450, 84, 1, 1855570, 5051988, 3246068, 789824, 86940, 4592, 112, 1, 26097835, 86910426, 68151304, 20606796, 2919504, 210924, 7896, 144, 1
Offset: 1

Views

Author

Christian G. Bower, Feb 15 1999

Keywords

Examples

			Triangle begins
      1;
      4,     1;
     22,    12,    1;
    154,   136,   24,    1;
   1304,  1650,  460,   40,  1;
  12915, 21904, 8550, 1160, 60, 1;
  ...
		

Crossrefs

Cf. A008277, A000307 (first column).

Programs

  • Mathematica
    Flatten[Table[SeriesCoefficient[(Exp[Exp[Exp[Exp[x]-1]-1]-1]-1)^k, {x,0,n}]  n!/k!, {n,9}, {k,n}]] (* Stefano Spezia, Sep 12 2022 *)

Formula

E.g.f. k-th column: (( exp(exp(exp(exp(x)-1)-1)-1)-1 )^k)/k!. [corrected by Seiichi Manyama, Feb 12 2022]

A351513 Expansion of e.g.f. (exp(exp(exp(x)-1)-1)-1)^2 / 2.

Original entry on oeis.org

1, 9, 75, 660, 6288, 65051, 728556, 8792910, 113805204, 1572387410, 23094192960, 359209182397, 5896792771795, 101854538628396, 1846058978130172, 35021271971160507, 693843099578350329, 14326635965967487711, 307729547549467823822, 6864250658908517748384
Offset: 2

Views

Author

Seiichi Manyama, Feb 12 2022

Keywords

Crossrefs

Column 2 of A039811.

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec(serlaplace((exp(exp(exp(x)-1)-1)-1)^2/2))
    
  • PARI
    T(n, k) = if(k==0, n<=1, sum(j=0, n, stirling(n, j, 2)*T(j, k-1)));
    a(n) = sum(k=1, n-1, binomial(n-1, k)*T(k, 3)*T(n-k, 3));

Formula

a(n) = Sum_{k=1..n-1} binomial(n-1,k) * A000258(k) * A000258(n-k).
Showing 1-6 of 6 results.