A144643 -id:A144643 - cp's OEIS frontend

A144644 Triangle in A144643 read by columns downwards.

1, 0, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 7, 6, 1, 0, 0, 15, 25, 10, 1, 0, 0, 25, 90, 65, 15, 1, 0, 0, 35, 280, 350, 140, 21, 1, 0, 0, 35, 770, 1645, 1050, 266, 28, 1, 0, 0, 0, 1855, 6930, 6825, 2646, 462, 36, 1, 0, 0, 0, 3675, 26425, 39795, 22575, 5880, 750, 45, 1

Offset: 0

David Applegate and N. J. A. Sloane, Jan 25 2009

The Bell transform of the sequence "g(n) = 1 if n<4 else 0". For the definition of the Bell transform see A264428. - Peter Luschny, Jan 19 2016

			Triangle begins:
  1;
  0, 1;
  0, 1,  1;
  0, 1,  3,    1;
  0, 1,  7,    6,     1;
  0, 0, 15,   25,    10,      1;
  0, 0, 25,   90,    65,     15,      1;
  0, 0, 35,  280,   350,    140,     21,     1;
  0, 0, 35,  770,  1645,   1050,    266,    28,     1;
  0, 0,  0, 1855,  6930,   6825,   2646,   462,    36,    1;
  0, 0,  0, 3675, 26425,  39795,  22575,  5880,   750,   45,  1;
  0, 0,  0, 5775, 90475, 211750, 172095, 63525, 11880, 1155, 55, 1;

G. C. Greubel, Rows n = 0..50 of the triangle, flattened
Moa Apagodu, David Applegate, N. J. A. Sloane, and Doron Zeilberger, Analysis of the Gift Exchange Problem, arXiv:1701.08394 [math.CO], 2017.
David Applegate and N. J. A. Sloane, The Gift Exchange Problem, arXiv:0907.0513 [math.CO], 2009.

Cf. A001681 (row sums), A111246, A122848, A144643, A144645, A151509, A151511, A264428.

function t(n,k)
  if k eq n then return 1;
  elif k le n-1 or n le 0 then return 0;
  else return (&+[Binomial(k-1,j)*t(n-1,k-j-1): j in [0..3]]);
  end if;
end function;
A144644:= func< n,k | t(k,n) >;
[A144644(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Oct 11 2023

With[{r=15}, Table[BellY[n, k, {1,1,1,1}], {n,0,r}, {k,0,n}]]//Flatten (* Jan Mangaldan, May 22 2016 *)

\\ Function bell_matrix is defined in A264428.
B = bell_matrix( n -> {if(n < 4, 1, 0)}, 9); for(n = 0, 9, printp(); for(k = 1, n, print1(B[n,k], " "))); \\ Peter Luschny, Apr 17 2019

# uses[bell_matrix from A264428]
bell_matrix(lambda n: 1 if n<4 else 0, 12) # Peter Luschny, Jan 19 2016

Bivariate e.g.f. A144644(x,t) = Sum_{n>=0, k>=0} T(n,k)*x^n*t^k/n! = exp(t*G4(x)), where G4(x) = Sum_{i=1..4} x^i/i! is the e.g.f. of column 1. - R. J. Mathar, May 28 2019
From G. C. Greubel, Oct 11 2023: (Start)
T(n, k) = A144643(k, n).
T(n, k) = A144645(n, n-k).
T(n, k) = t(k, n), where t(n, k) = Sum_{j=0..3} binomial(k-1, j) * t(n-1, k-j-1), with t(n,n) = 1, t(n,k) = 0 if n < 1 or n > k.
Sum_{k=0..n} T(n, k) = A001681(n). (End)

A144645 Triangle in A144643 read upwards by columns.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 6, 7, 1, 0, 1, 10, 25, 15, 0, 0, 1, 15, 65, 90, 25, 0, 0, 1, 21, 140, 350, 280, 35, 0, 0, 1, 28, 266, 1050, 1645, 770, 35, 0, 0, 1, 36, 462, 2646, 6825, 6930, 1855, 0, 0, 0, 1, 45, 750, 5880, 22575, 39795, 26425, 3675, 0, 0, 0

Offset: 0

David Applegate and N. J. A. Sloane, Jan 25 2009

			Triangle begins:
  1;
  1,  0;
  1,  1,   0;
  1,  3,   1,    0;
  1,  6,   7,    1,     0;
  1, 10,  25,   15,     0,     0;
  1, 15,  65,   90,    25,     0,     0;
  1, 21, 140,  350,   280,    35,     0,    0;
  1, 28, 266, 1050,  1645,   770,    35,    0,   0;
  1, 36, 462, 2646,  6825,  6930,  1855,    0,   0,   0;
  1, 45, 750, 5880, 22575, 39795, 26425, 3675,   0,   0,   0;

G. C. Greubel, Rows n = 0..50 of the triangle, flattened
Moa Apagodu, David Applegate, N. J. A. Sloane, and Doron Zeilberger, Analysis of the Gift Exchange Problem, arXiv:1701.08394 [math.CO], 2017.
David Applegate and N. J. A. Sloane, The Gift Exchange Problem, arXiv:0907.0513 [math.CO], 2009.

Cf. A001681 (row sums), A144643, A144644.

function t(n,k)
  if k eq n then return 1;
  elif k le n-1 or n le 0 then return 0;
  else return (&+[Binomial(k-1,j)*t(n-1,k-j-1): j in [0..3]]);
  end if;
end function;
A144645:= func< n,k | t(n-k,n) >;
[A144645(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Oct 11 2023

Table[BellY[n, n-k, {1,1,1,1}], {n,0,15}, {k,0,n}]//Flatten (* G. C. Greubel, Oct 11 2023; based on A144644 *)

@CachedFunction
def t(n,k):
    if (k==n): return 1
    elif (kA144645(n,k): return t(n-k,n)
flatten([[A144645(n,k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Oct 11 2023

From G. C. Greubel, Oct 11 2023: (Start)
T(n, k) = A144643(n-k, n).
T(n, k) = A144644(n, n-k).
T(n, k) = t(n-k, n), where t(n, k) = Sum_{j=0..3} binomial(k-1, j) * t(n-1, k-j-1), with t(n,n) = 1, t(n,k) = 0 if n < 1 or n > k.
Sum_{k=0..n} T(n, k) = A001681(n). (End)

A144385 Triangle read by rows: T(n,k) is the number of partitions of [1, 2, ..., k] into exactly n blocks, each of size 1, 2 or 3 (n >= 0, 0 <= k <= 3n).

Original entry on oeis.org

1, 0, 1, 1, 1, 0, 0, 1, 3, 7, 10, 10, 0, 0, 0, 1, 6, 25, 75, 175, 280, 280, 0, 0, 0, 0, 1, 10, 65, 315, 1225, 3780, 9100, 15400, 15400, 0, 0, 0, 0, 0, 1, 15, 140, 980, 5565, 26145, 102025, 323400, 800800, 1401400, 1401400, 0, 0, 0, 0, 0, 0, 1, 21, 266, 2520, 19425, 125895, 695695, 3273270, 12962950, 42042000, 106506400, 190590400, 190590400

Offset: 0

David Applegate and N. J. A. Sloane, Dec 07 2008, Dec 17 2008

Row n has 3n+1 entries.

			Triangle begins:
[1]
[0, 1, 1, 1]
[0, 0, 1, 3, 7, 10, 10]
[0, 0, 0, 1, 6, 25, 75, 175, 280, 280]
[0, 0, 0, 0, 1, 10, 65, 315, 1225, 3780, 9100, 15400, 15400]
[0, 0, 0, 0, 0, 1, 15, 140, 980, 5565, 26145, 102025, 323400, 800800, 1401400, 1401400]

Moa Apagodu, David Applegate, N. J. A. Sloane, and Doron Zeilberger, Analysis of the Gift Exchange Problem, arXiv:1701.08394, 2017.
David Applegate and N. J. A. Sloane, The Gift Exchange Problem (arXiv:0907.0513, 2009)

See A144399, A144402, A144417, A111246 for other versions of this triangle.
Column sums give A001680, row sums give A144416. Taking last nonzero entry in each row gives A025035.
Diagonals include A000217, A001296, A027778, A144516; also A025035.
A generalization of the triangle in A144331 (and in several other entries).
Cf. A144643.

T := proc(n, k)
option remember;
if n = k then 1;
elif k < n then 0;
elif n < 1 then 0;
else T(n - 1, k - 1) + (k - 1)*T(n - 1, k - 2) + 1/2*(k - 1)*(k - 2)*T(n - 1, k - 3);
end if;
end proc;
for n from 0 to 12 do lprint([seq(T(n,k),k=0..3*n)]); od:

t[n_, n_] = 1; t[n_ /; n >= 0, k_] /; 0 <= k <= 3*n := t[n, k] = t[n-1, k-1] + (k-1)*t[n-1, k-2] + (1/2)*(k-1)*(k-2)*t[n-1, k-3]; t[, ] = 0; Table[t[n, k], {n, 0, 12}, {k, 0, 3*n}] // Flatten (* Jean-François Alcover, Jan 14 2014 *)

T(n, k) = T(n - 1, k - 1) + (k - 1)*T(n - 1, k - 2) + (1/2)*(k - 1)*(k - 2)*T(n - 1, k - 3).

E.g.f.: Sum_{ n >= 0, k >= 0 } T(n, k) y^n x^k / k! = exp( y*(x+x^2/2+x^3/6) ). That is, the coefficient of y^n is the e.g.f. for row n. E.g. the e.g.f. for row 2 is (1/2)*(x+x^2/2+x^3/6)^2 = 1*x^2/2! + 3*x^3/3! + 7*x^4/4! + 10*x^5/5! + 10*x^6/6!.

A144299 Triangle of Bessel numbers read by rows. Row n gives T(n,n), T(n,n-1), T(n,n-2), ..., T(n,0) for n >= 0.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 3, 0, 0, 1, 6, 3, 0, 0, 1, 10, 15, 0, 0, 0, 1, 15, 45, 15, 0, 0, 0, 1, 21, 105, 105, 0, 0, 0, 0, 1, 28, 210, 420, 105, 0, 0, 0, 0, 1, 36, 378, 1260, 945, 0, 0, 0, 0, 0, 1, 45, 630, 3150, 4725, 945, 0, 0, 0, 0, 0, 1, 55, 990, 6930, 17325, 10395, 0, 0, 0, 0, 0, 0

Offset: 0

David Applegate and N. J. A. Sloane, Dec 06 2008

T(n,k) is the number of partitions of an n-set into k nonempty subsets, each of size at most 2.
The Grosswald and Choi-Smith references give many further properties and formulas.
Considered as an infinite lower triangular matrix T, lim_{n->infinity} T^n = A118930: (1, 1, 2, 4, 13, 41, 166, 652, ...) as a vector. - Gary W. Adamson, Dec 08 2008

			Triangle begins:
  n:
  0: 1
  1: 1  0
  2: 1  1   0
  3: 1  3   0    0
  4: 1  6   3    0   0
  5: 1 10  15    0   0  0
  6: 1 15  45   15   0  0  0
  7: 1 21 105  105   0  0  0  0
  8: 1 28 210  420 105  0  0  0  0
  9: 1 36 378 1260 945  0  0  0  0  0
  ...
The row sums give A000085.
For some purposes it is convenient to rotate the triangle by 45 degrees:
  1 0 0 0 0  0  0   0   0    0    0     0 ...
    1 1 0 0  0  0   0   0    0    0     0 ...
      1 3 3  0  0   0   0    0    0     0 ...
        1 6 15 15   0   0    0    0     0 ...
          1 10 45 105 105    0    0     0 ...
             1 15 105 420  945  945     0 ...
                1  21 210 1260 4725 10395 ...
                    1  28  378 3150 17325 ...
                        1   36  630  6930 ...
                             1   45   990 ...
  ...
The latter triangle is important enough that it has its own entry, A144331. Here the column sums give A000085 and the rows sums give A001515.
If the entries in the rotated triangle are denoted by b1(n,k), n >= 0, k <= 2n, then we have the recurrence b1(n, k) = b1(n - 1, k - 1) + (k - 1)*b1(n - 1, k - 2).
Then b1(n,k) is the number of partitions of [1, 2, ..., k] into exactly n blocks, each of size 1 or 2.

E. Grosswald, Bessel Polynomials, Lecture Notes Math., Vol. 698, 1978.

Reinhard Zumkeller, Rows n = 0..125 of triangle, flattened
David Applegate and N. J. A. Sloane, The Gift Exchange Problem, arXiv:0907.0513 [math.CO], 2009.
J. Y. Choi and J. D. H. Smith, On the unimodality and combinatorics of Bessel numbers, Discrete Math., 264 (2003), 45-53.
Tom Copeland, Infinitesimal Generators, the Pascal Pyramid, and the Witt and Virasoro Algebras
Toufik Mansour, Matthias Schork, and Mark Shattuck, The Generalized Stirling and Bell Numbers Revisited, Journal of Integer Sequences, Vol. 15 (2012), #12.8.3.
T. Mansour and M. Shattuck, Partial matchings and pattern avoidance, Appl. Anal. Discrete Math. 7 (2013) 25-50.

Other versions of this same triangle are given in A111924 (which omits the first row), A001498 (which left-adjusts the rows in the bottom view), A001497 and A100861. Row sums give A000085.

Cf. A000085, A000217, A001464, A004526, A118930, A144385, A144643..

a144299 n k = a144299_tabl !! n !! k
a144299_row n = a144299_tabl !! n
a144299_tabl = [1] : [1, 0] : f 1 [1] [1, 0] where
   f i us vs = ws : f (i + 1) vs ws where
               ws = (zipWith (+) (0 : map (i *) us) vs) ++ [0]
-- Reinhard Zumkeller, Jan 01 2014

A144299:= func< n,k | k le Floor(n/2) select Factorial(n)/(Factorial(n-2*k)*Factorial(k)*2^k) else 0 >;
[A144299(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Sep 29 2023

Maple code producing the rotated version:
b1 := proc(n, k)
option remember;
if n = k then 1;
elif k < n then 0;
elif n < 1 then 0;
else b1(n - 1, k - 1) + (k - 1)*b1(n - 1, k - 2);
end if;
end proc;
for n from 0 to 12 do lprint([seq(b1(n,k),k=0..2*n)]); od:

T[n_,0]=0; T[1,1]=1; T[2,1]=1; T[n_, k_]:= T[n-1,k-1] + (n-1)T[n-2,k-1];
Table[T[n,k], {n,12}, {k,n,1,-1}]//Flatten (* Robert G. Wilson v *)
Table[If[k<=Floor[n/2],n!/((n-2 k)! k! 2^k),0], {n, 0, 12},{k,0,n}]//Flatten (* Stefano Spezia, Jun 15 2023 *)

def A144299(n,k): return factorial(n)/(factorial(n-2*k)*factorial(k)*2^k) if k <= (n//2) else 0
flatten([[A144299(n,k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Sep 29 2023

T(n, k) = T(n-1, k-1) + (n-1)*T(n-2, k-1).
E.g.f.: Sum_{k >= 0} Sum_{n = 0..2k} T(n,k) y^k x^n/n! = exp(y(x+x^2/2)). (The coefficient of y^k is the e.g.f. for the k-th row of the rotated triangle shown below.)
T(n, k) = n!/((n - 2*k)!*k!*2^k) for 0 <= k <= floor(n/2) and 0 otherwise. - Stefano Spezia, Jun 15 2023
From G. C. Greubel, Sep 29 2023: (Start)
T(n, 1) = A000217(n-1).
Sum_{k=0..n} T(n,k) = A000085(n).
Sum_{k=0..n} (-1)^k*T(n,k) = A001464(n). (End)

Offset fixed by Reinhard Zumkeller, Jan 01 2014

A151338 Triangle read by rows: T(n,k) = number of partitions of [1..k] into n nonempty clumps of sizes 1, 2, 3, 4 or 5 (n >= 0, 0 <= k <= 5n).

Original entry on oeis.org

1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 3, 7, 15, 31, 56, 91, 126, 126, 0, 0, 0, 1, 6, 25, 90, 301, 938, 2737, 7455, 18711, 41811, 81081, 126126, 126126, 0, 0, 0, 0, 1, 10, 65, 350, 1701, 7686, 32725, 132055, 505351, 1824823, 6173167, 19339320, 55096041

Offset: 0

N. J. A. Sloane, May 13 2009

Row n has 5n+1 entries.

			The triangle begins:
1
0, 1, 1, 1, 1, 1
0, 0, 1, 3, 7, 15, 31, 56, 91, 126, 126
0, 0, 0, 1, 6, 25, 90, 301, 938, 2737, 7455, 18711, 41811, 81081, 126126, 126126
0, 0, 0, 0, 1, 10, 65, 350, 1701, 7686, 32725, 132055, 505351, 1824823, 6173167, 19339320, 55096041, 138654516, 295891596, 488864376, 488864376
0, 0, 0, 0, 0, 1, 15, 140, 1050, 6951, 42315, 241780, 1310925, 6782776, 33549516, 158533375, 713733020, 3046944901, 12246267033, 45892143297, 158167994985, 491492022021, 1336310771796, 3030225834636, 5194672859376, 5194672859376
...

Moa Apagodu, David Applegate, N. J. A. Sloane, and Doron Zeilberger, Analysis of the Gift Exchange Problem, arXiv:1701.08394, 2017.
David Applegate and N. J. A. Sloane, The Gift Exchange Problem (arXiv:0907.0513, 2009)

This is one of a sequence of triangles: A144331, A144385, A144643, A151338, A151359, ...

See A151509, A151510 for other versions.

A151359 Triangle read by rows: T(n,k) = number of partitions of [1..k] into n nonempty clumps of sizes 1, 2, 3, 4, 5 or 6 (n >= 0, 0 <= k <= 6n).

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 3, 7, 15, 31, 63, 119, 210, 336, 462, 462, 0, 0, 0, 1, 6, 25, 90, 301, 966, 2989, 8925, 25641, 70455, 183183, 441441, 966966, 1849848, 2858856, 2858856, 0, 0, 0, 0, 1, 10, 65, 350, 1701, 7770, 33985, 143605, 588511

Offset: 0

N. J. A. Sloane, May 14 2009

Row n has 6n+1 entries.

			Triangle begins:
[0, 1, 1, 1, 1, 1, 1]
[0, 0, 1, 3, 7, 15, 31, 63, 119, 210, 336, 462, 462]
[0, 0, 0, 1, 6, 25, 90, 301, 966, 2989, 8925, 25641, 70455, 183183, 441441, 966966, 1849848, 2858856, 2858856]
[0, 0, 0, 0, 1, 10, 65, 350, 1701, 7770, 33985, 143605, 588511, 2341339, 9032023, 33668635, 120681561, 413104692, 1337944608, 4046710668, 11216721516, 27756632904, 58555088592, 96197645544, 96197645544]
[0, 0, 0, 0, 0, 1, 15, 140, 1050, 6951, 42525, 246400, 1370985, 7383376, 38657619, 197212015, 980839860, 4752728981, 22399494117, 102410296989, 452572985865, 1924000439361, 7820764020069, 30157961878044, 109184327692440, 365935843649376, 1113006758944080, 2982608000091720, 6696799094545560, 11423951396577720, 11423951396577720]
...

Moa Apagodu, David Applegate, N. J. A. Sloane, and Doron Zeilberger, Analysis of the Gift Exchange Problem, arXiv:1701.08394, 2017.
David Applegate and N. J. A. Sloane, The Gift Exchange Problem, arXiv:0907.0513 [math.CO], 2009.

This is one of a sequence of triangles: A144331, A144385, A144643, A151338, A151359, ...

See A151511, A151512 for other versions.

Unprotect[Power]; 0^0 = 1; a[n_ /; 1 <= n <= 6] = 1; a[] = 0; t[n, k_] := t[n, k] = If[k == 0, a[0]^n, Sum[Binomial[n-1, j-1] a[j] t[n-j, k-1], {j, 0, n-k+1}]]; T[n_, k_] := t[k, n+1]; Table[Table[T[n, k], {k, 0, 6(n+1)} ], {n, 0, 4}] // Flatten (* Jean-François Alcover, Jan 20 2016, using Peter Luschny's Bell transform *)

cp's OEIS Frontend

A144644 Triangle in A144643 read by columns downwards.

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A144645 Triangle in A144643 read upwards by columns.

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A144385 Triangle read by rows: T(n,k) is the number of partitions of [1, 2, ..., k] into exactly n blocks, each of size 1, 2 or 3 (n >= 0, 0 <= k <= 3n).

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A144299 Triangle of Bessel numbers read by rows. Row n gives T(n,n), T(n,n-1), T(n,n-2), ..., T(n,0) for n >= 0.

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A151338 Triangle read by rows: T(n,k) = number of partitions of [1..k] into n nonempty clumps of sizes 1, 2, 3, 4 or 5 (n >= 0, 0 <= k <= 5n).

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A151359 Triangle read by rows: T(n,k) = number of partitions of [1..k] into n nonempty clumps of sizes 1, 2, 3, 4, 5 or 6 (n >= 0, 0 <= k <= 6n).

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