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 10 results.

A157400 A partition product with biggest-part statistic of Stirling_1 type (with parameter k = -2) as well as of Stirling_2 type (with parameter k = -2), (triangle read by rows).

Original entry on oeis.org

1, 1, 2, 1, 6, 6, 1, 24, 24, 24, 1, 80, 180, 120, 120, 1, 330, 1200, 1080, 720, 720, 1, 1302, 7770, 10920, 7560, 5040, 5040, 1, 5936, 57456, 102480, 87360, 60480, 40320, 40320, 1, 26784, 438984, 970704, 1103760, 786240, 544320, 362880, 362880
Offset: 1

Views

Author

Peter Luschny, Mar 09 2009, Mar 14 2009

Keywords

Comments

Partition product of Product_{j=0..n-1} ((k+1)*j - 1) and n! at k = -2, summed over parts with equal biggest part (Stirling_2 type) as well as partition product of Product_{j=0..n-2} (k-n+j+2) and n! at k = -2 (Stirling_1 type).
It shares this property with the signless Lah numbers.
Underlying partition triangle is A130561.
Same partition product with length statistic is A105278.
Diagonal a(A000217) = A000142.
Row sum is A000262.
T(n,k) is the number of nilpotent elements in the symmetric inverse semigroup (partial bijections) on [n] having index k. Equivalently, T(n,k) is the number of directed acyclic graphs on n labeled nodes with every node having indegree and outdegree at most one and the longest path containing exactly k nodes. - Geoffrey Critzer, Nov 21 2021

Examples

			Triangle starts:
  1;
  1,   2;
  1,   6,    6;
  1,  24,   24,   24;
  1,  80,  180,  120, 120;
  1, 330, 1200, 1080, 720, 720;
  ...
		

Crossrefs

Programs

  • Maple
    egf:= k-> exp((x^(k+1)-x)/(x-1))-exp((x^k-x)/(x-1)):
    T:= (n, k)-> n!*coeff(series(egf(k), x, n+1), x, n):
    seq(seq(T(n, k), k=1..n), n=1..10);  # Alois P. Heinz, Oct 10 2015
  • Mathematica
    egf[k_] := Exp[(x^(k+1)-x)/(x-1)] - Exp[(x^k-x)/(x-1)]; T[n_, k_] := n! * SeriesCoefficient[egf[k], {x, 0, n}]; Table[Table[T[n, k], {k, 1, n}], {n, 1, 10}] // Flatten (* Jean-François Alcover, Oct 11 2015, after Alois P. Heinz *)

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n.
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,...,a_n such that
1*a_1 + 2*a_2 + ... + n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = Product_{j=0..n-1} (-j-1)
OR f_n = Product_{j=0..n-2} (j-n) since both have the same absolute value n!.
E.g.f. of column k: exp((x^(k+1)-x)/(x-1))-exp((x^k-x)/(x-1)). - Alois P. Heinz, Oct 10 2015

A126074 Triangle read by rows: T(n,k) is the number of permutations of n elements that have the longest cycle length k.

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 1, 9, 8, 6, 1, 25, 40, 30, 24, 1, 75, 200, 180, 144, 120, 1, 231, 980, 1260, 1008, 840, 720, 1, 763, 5152, 8820, 8064, 6720, 5760, 5040, 1, 2619, 28448, 61236, 72576, 60480, 51840, 45360, 40320, 1, 9495, 162080, 461160, 653184, 604800, 518400, 453600, 403200, 362880
Offset: 1

Views

Author

Dan Dima, Mar 01 2007

Keywords

Comments

Sum of the n-th row is the number of all permutations of n elements: Sum_{k=1..n, T(n,k)} = n! = A000142(n) We can extend T(n,k)=0, if k<=0 or k>n.
From Peter Luschny, Mar 07 2009: (Start)
Partition product of prod_{j=0..n-2}(k-n+j+2) and n! at k = -1, summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A102189.
Same partition product with length statistic is A008275.
Diagonal a(A000217(n)) = rising_factorial(1,n-1), A000142(n-1) (n > 0).
Row sum is A000142. (End)
Let k in {1,2,3,...} index the family of sequences A000012, A000085, A057693, A070945, A070946, A070947, ... respectively. Column k is the k-th sequence minus its immediate predecessor. For example, T(5,3)=A057693(5)-A000085(5). - Geoffrey Critzer, May 23 2009

Examples

			Triangle T(n,k) begins:
  1;
  1,   1;
  1,   3,    2;
  1,   9,    8,    6;
  1,  25,   40,   30,   24;
  1,  75,  200,  180,  144,  120;
  1, 231,  980, 1260, 1008,  840,  720;
  1, 763, 5152, 8820, 8064, 6720, 5760, 5040;
  ...
		

Crossrefs

Cf. A000142.
T(2n,n) gives A052145 (for n>0). - Alois P. Heinz, Apr 21 2017

Programs

  • Maple
    A:= proc(n,k) option remember; `if`(n<0, 0, `if`(n=0, 1,
           add(mul(n-i, i=1..j-1)*A(n-j,k), j=1..k)))
        end:
    T:= (n, k)-> A(n, k) -A(n, k-1):
    seq(seq(T(n,k), k=1..n), n=1..10);  # Alois P. Heinz, Feb 11 2013
  • Mathematica
    Table[CoefficientList[ Series[(Exp[x^m/m] - 1) Exp[Sum[x^k/k, {k, 1, m - 1}]], {x, 0, 8}], x]*Table[n!, {n, 0, 8}], {m, 1, 8}] // Transpose // Grid (* Geoffrey Critzer, May 23 2009 *)
  • Sage
    def A126074(n, k):
        f = factorial(n)
        P = Partitions(n, max_part=k, inner=[k])
        return sum(f // p.aut() for p in P)
    for n in (1..9): print([A126074(n,k) for k in (1..n)]) # Peter Luschny, Apr 17 2016

Formula

T(n,1) = 1.
T(n,2) = n! * Sum_{k=1..[n/2]} 1/(k! * (2!)^k * (n-2*k)!).
T(n,k) = n!/k * (1-1/(n-k)-...-1/(k+1)-1/2k), if n/3 < k <= n/2.
T(n,k) = n!/k, if n/2 < k <= n.
T(n,n) = (n-1)! = A000142(n-1).
E.g.f. for k-th column: exp(-x^k*LerchPhi(x,1,k))*(exp(x^k/k)-1)/(1-x). - Vladeta Jovovic, Mar 03 2007
From Peter Luschny, Mar 07 2009: (Start)
T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = product_{j=0..n-2}(j-n+1). (End)
Sum_{k=1..n} k * T(n,k) = A028418(n). - Alois P. Heinz, May 17 2016

A157394 A partition product of Stirling_1 type [parameter k = 4] with biggest-part statistic (triangle read by rows).

Original entry on oeis.org

1, 1, 4, 1, 12, 12, 1, 72, 48, 24, 1, 280, 600, 120, 24, 1, 1740, 4560, 1800, 144, 0, 1, 8484, 40740, 21000, 2520, 0, 0, 1, 57232, 390432, 223440, 33600, 0, 0, 0, 1, 328752, 3811248, 2845584, 438480, 0, 0, 0, 0, 1, 2389140
Offset: 1

Views

Author

Peter Luschny, Mar 07 2009, Mar 14 2009

Keywords

Comments

Partition product of prod_{j=0..n-2}(k-n+j+2) and n! at k = 4,
summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A144878.
Same partition product with length statistic is A049424.
Diagonal a(A000217(n)) = falling_factorial(4,n-1), row in A008279
Row sum is A049427.

Examples

			1
1       4
1      12       12
1      72       48       24
1     280      600      120      24
1    1740     4560     1800     144  0
1    8484    40740    21000    2520  0  0
1   57232   390432   223440   33600  0  0  0
1  328752  3811248  2845584  438480  0  0  0  0
1  2389140
		

Crossrefs

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = product_{j=0..n-2}(j-n+6).

A157391 A partition product of Stirling_1 type [parameter k = 1] with biggest-part statistic (triangle read by rows).

Original entry on oeis.org

1, 1, 1, 1, 3, 0, 1, 9, 0, 0, 1, 25, 0, 0, 0, 1, 75, 0, 0, 0, 0, 1, 231, 0, 0, 0, 0, 0, 1, 763, 0, 0, 0, 0, 0, 0, 1, 2619, 0, 0, 0, 0, 0, 0, 0, 1, 9495, 0, 0, 0, 0, 0, 0, 0, 0, 1, 35695, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 140151
Offset: 1

Views

Author

Peter Luschny, Mar 07 2009, Mar 14 2009

Keywords

Comments

Partition product of prod_{j=0..n-2}(k-n+j+2) and n! at k = 1,
summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A144357.
Same partition product with length statistic is A049403.
Diagonal a(A000217(n)) = falling_factorial(1,n-1), row in A008279.
Row sum is A000085.

Crossrefs

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = product_{j=0..n-2}(j-n+3).

A157392 A partition product of Stirling_1 type [parameter k = 2] with biggest-part statistic (triangle read by rows).

Original entry on oeis.org

1, 1, 2, 1, 6, 2, 1, 24, 8, 0, 1, 80, 60, 0, 0, 1, 330, 320, 0, 0, 0, 1, 1302, 2030, 0, 0, 0, 0, 1, 5936, 12432, 0, 0, 0, 0, 0, 1, 26784, 81368, 0, 0, 0, 0, 0, 0, 1, 133650, 545120, 0, 0, 0, 0, 0, 0, 0, 1, 669350, 3825690
Offset: 1

Views

Author

Peter Luschny, Mar 07 2009, Mar 14 2009

Keywords

Comments

Partition product of prod_{j=0..n-2}(k-n+j+2) and n! at k = 2,
summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A144358.
Same partition product with length statistic is A049404.
Diagonal a(A000217(n)) = falling_factorial(2,n-1), row in A008279
Row sum is A049425.

Crossrefs

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = = product_{j=0..n-2}(j-n+4).

A157393 A partition product of Stirling_1 type [parameter k = 3] with biggest-part statistic (triangle read by rows).

Original entry on oeis.org

1, 1, 3, 1, 9, 6, 1, 45, 24, 6, 1, 165, 240, 30, 0, 1, 855, 1560, 360, 0, 0, 1, 3843, 12180, 3360, 0, 0, 0, 1, 21819, 96096, 30660, 0, 0, 0, 0, 1, 114075, 794304, 318276, 0, 0, 0, 0, 0, 1, 703215, 6850080, 3270960, 0, 0, 0, 0, 0, 0, 1, 4125495, 62516520, 35053920, 0, 0
Offset: 1

Views

Author

Peter Luschny, Mar 07 2009, Mar 14 2009

Keywords

Comments

Partition product prod_{j=0..n-2}(k-n+j+2) and n! at k = 3, summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A144877.
Same partition product with length statistic is A049410.
Diagonal a(A000217(n)) = falling_factorial(3,n-1), row in A008279.
Row sum is A049426.

Crossrefs

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = product_{j=0..n-2}(j-n+5).

A157395 A partition product of Stirling_1 type [parameter k = 5] with biggest-part statistic (triangle read by rows).

Original entry on oeis.org

1, 1, 5, 1, 15, 20, 1, 105, 80, 60, 1, 425, 1200, 300, 120, 1, 3075, 10400, 5400, 720, 120, 1, 15855, 102200, 75600, 15120, 840, 0, 1, 123515, 1149120, 907200, 241920, 20160, 0, 0, 1, 757755, 12783680, 13426560, 3719520, 362880
Offset: 1

Views

Author

Peter Luschny, Mar 07 2009, Mar 14 2009

Keywords

Comments

Partition product of prod_{j=0..n-2}(k-n+j+2) and n! at k = 5,
summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A144879.
Same partition product with length statistic is A049411.
Diagonal a(A000217(n)) = falling_factorial(5,n-1), row in A008279
Row sum is A049428.

Crossrefs

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = product_{j=0..n-2}(j-n+7).

A157383 A partition product of Stirling_1 type [parameter k = -3] with biggest-part statistic (triangle read by rows).

Original entry on oeis.org

1, 1, 3, 1, 9, 12, 1, 45, 48, 60, 1, 165, 480, 300, 360, 1, 855, 3840, 3600, 2160, 2520, 1, 3843, 29400, 46200, 30240, 17640, 20160, 1, 21819, 272832, 520800, 443520, 282240, 161280, 181440
Offset: 1

Views

Author

Peter Luschny, Mar 07 2009, Mar 14 2009

Keywords

Comments

Partition product of prod_{j=0..n-2}(k-n+j+2) and n! at k = -3,
summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A144353.
Same partition product with length statistic is A046089.
Diagonal a(A000217(n)) = rising_factorial(3,n-1), A001710(n+1).
Row sum is A049376.

Crossrefs

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = product_{j=0..n-2}(j-n-1).

A157386 A partition product of Stirling_1 type [parameter k = -6] with biggest-part statistic (triangle read by rows).

Original entry on oeis.org

1, 1, 6, 1, 18, 42, 1, 144, 168, 336, 1, 600, 2940, 1680, 3024, 1, 4950, 33600, 35280, 18144, 30240, 1, 26586, 336630, 717360, 444528, 211680, 332640, 1, 234528, 4870992, 11313120, 10329984, 5927040, 2661120, 3991680
Offset: 1

Views

Author

Peter Luschny, Mar 07 2009, Mar 14 2009

Keywords

Comments

Partition product of prod_{j=0..n-2}(k-n+j+2) and n! at k = -6,
summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A144356.
Same partition product with length statistic is A049374.
Diagonal a(A000217(n)) = rising_factorial(6,n-1), A001725(n+4).
Row sum is A049402.

Crossrefs

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = product_{j=0..n-2}(j-n-4).

A157385 A partition product of Stirling_1 type [parameter k = -5] with biggest-part statistic (triangle read by rows).

Original entry on oeis.org

1, 1, 5, 1, 15, 30, 1, 105, 120, 210, 1, 425, 1800, 1050, 1680, 1, 3075, 18600, 18900, 10080, 15120, 1, 15855, 174300, 338100, 211680, 105840, 151200, 1, 123515, 2227680, 4865700, 4327680, 2540160, 1209600, 1663200, 1, 757755
Offset: 1

Views

Author

Peter Luschny, Mar 07 2009, Mar 14 2009

Keywords

Comments

Partition product of prod_{j=0..n-2}(k-n+j+2) and n! at k = -5,
summed over parts with equal biggest part (see the Luschny link).
Underlying partition triangle is A144355.
Same partition product with length statistic is A049353.
Diagonal a(A000217(n)) = rising_factorial(5,n-1), A001720(n+3).
Row sum is A049378.

Crossrefs

Formula

T(n,0) = [n = 0] (Iverson notation) and for n > 0 and 1 <= m <= n
T(n,m) = Sum_{a} M(a)|f^a| where a = a_1,..,a_n such that
1*a_1+2*a_2+...+n*a_n = n and max{a_i} = m, M(a) = n!/(a_1!*..*a_n!),
f^a = (f_1/1!)^a_1*..*(f_n/n!)^a_n and f_n = product_{j=0..n-2}(j-n-3).
Showing 1-10 of 10 results.