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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A144510 Array T(n,k) (n >= 1, k >= 0) read by downwards antidiagonals: T(n,k) = total number of partitions of [1, 2, ..., i] into exactly k nonempty blocks, each of size at most n, for any i in the range n <= i <= k*n.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 7, 3, 1, 1, 37, 31, 4, 1, 1, 266, 842, 121, 5, 1, 1, 2431, 45296, 18252, 456, 6, 1, 1, 27007, 4061871, 7958726, 405408, 1709, 7, 1, 1, 353522, 546809243, 7528988476, 1495388159, 9268549, 6427, 8, 1
Offset: 1

Views

Author

David Applegate and N. J. A. Sloane, Dec 15 2008, Jan 30 2009

Keywords

Examples

			Array begins:
1, 1,    1,       1,            1,                 1,                       1, ...
1, 2,    7,      37,          266,              2431,                   27007, ...
1, 3,   31,     842,        45296,           4061871,               546809243, ...
1, 4,  121,   18252,      7958726,        7528988476,          13130817809439, ...
1, 5,  456,  405408,   1495388159,    15467641899285,      361207016885536095, ...
1, 6, 1709, 9268549, 295887993624, 34155922905682979, 10893033763705794846727, ...
...
		

Crossrefs

For the transposed array see A144512.
Rows include A001515, A144416, A144508, A144509.
Columns include A048775, A144511.
A(n+1,n) gives A281901.
A(n,n) gives A308296.
Cf. A308292.

Programs

  • Maple
    b := proc(n, i, k) local r;
    option remember;
    if n = i then 1;
    elif i < n then 0;
    elif n < 1 then 0;
    else add( binomial(i-1,r)*b(n-1,i-1-r,k), r=0..k);
    end if;
    end proc;
    T:=proc(n,k); add(b(n,i,k),i=0..(k+1)*n); end proc;
    # Peter Luschny, Apr 26 2011
    A144510 := proc(n, k) local m;
    add(m!*coeff(expand((exp(x)*GAMMA(n+1,x)/GAMMA(n+1)-1)^k),x,m),m=k..k*n)/k! end: for row from 1 to 6 do seq(A144510(row, col), col = 0..5) od;
  • Mathematica
    multinomial[n_, k_List] := n!/Times @@ (k!); t[n_, k_] := Module[{i, ik}, ik = Array[i, k]; 1/k!* Sum[multinomial[Total[ik], ik], Evaluate[Sequence @@ Thread[{ik, 1, n}]]]]; Table[t[n-k, k], {n, 1, 10}, {k, n-1, 0, -1}] // Flatten (* Jean-François Alcover, Jan 14 2014 *)

Formula

T(n,k) = (1/k!)*Sum_{i_1=1..n} Sum_{i_2=1..n} ... Sum_{i_k=1..n} multinomial(i_1+i_2+...+i_k; i_1, i_2, ..., i_k).
T(n,k) = (1/k!)*Sum_{m=k..k*n} m! [x^m](e^x Gamma(n+1,x)/Gamma(n+1)-1)^k. Here [x^m]f(x) is the coefficient of x^m in the series expansion of f(x). - Peter Luschny, Apr 26 2011

A144512 Array read by upwards antidiagonals: T(n,k) = total number of partitions of [1, 2, ..., k] into exactly n blocks, each of size 1, 2, ..., k+1, for 0 <= k <= (k+1)*n.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 7, 1, 1, 4, 31, 37, 1, 1, 5, 121, 842, 266, 1, 1, 6, 456, 18252, 45296, 2431, 1, 1, 7, 1709, 405408, 7958726, 4061871, 27007, 1, 1, 8, 6427, 9268549, 1495388159, 7528988476, 546809243, 353522, 1, 1, 9, 24301, 216864652, 295887993624, 15467641899285
Offset: 0

Views

Author

David Applegate and N. J. A. Sloane, Dec 15 2008, Dec 21 2008

Keywords

Examples

			Array begins:
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
1, 2, 7, 37, 266, 2431, 27007, 353522, 5329837, ...
1, 3, 31, 842, 45296, 4061871, 546809243, 103123135501, ...
1, 4, 121, 18252, 7958726, 7528988476, 13130817809439, ...
1, 5, 456, 405408, 1495388159, 15467641899285, 361207016885536095, ...
1, 6, 1709, 9268549, 295887993624, 34155922905682979, 10893033763705794846727, ...
...
		

Crossrefs

See A144510 for Maple code.
Columns include A048775, A144511, A144662, A147984.
Transpose of array in A144510.
Main diagonal gives A281901.

Programs

  • Maple
    b := proc(n, i, k) local r;
    option remember;
    if n = i then 1;
    elif i < n then 0;
    elif n < 1 then 0;
    else add( binomial(i-1,r)*b(n-1,i-1-r,k), r=0..k);
    end if;
    end proc;
    T:=proc(n,k); add(b(n,i,k),i=0..(k+1)*n); end proc;
  • Mathematica
    multinomial[n_, k_List] := n!/Times @@ (k!); t[n_, k_] := Module[{i, ik}, ik = Array[i, k]; 1/k!* Sum[multinomial[Total[ik], ik], Evaluate[Sequence @@ Thread[{ik, 1, n}]]]]; Table[t[n-k, k], {n, 1, 10}, {k, 0, n-1}] // Flatten (* Jean-François Alcover, Jan 14 2014 *)

A144399 Triangle in A144385 with rows left-adjusted.

Original entry on oeis.org

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

Views

Author

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

Keywords

Comments

Row n has 2n+1 terms.

Examples

			Triangle begins:
1
1, 1, 1
1, 3, 7, 10, 10
1, 6, 25, 75, 175, 280, 280
1, 10, 65, 315, 1225, 3780, 9100, 15400, 15400
		

Crossrefs

Cf. A144385. Row sums give A144416.

Programs

  • Maple
    b:= proc(n) option remember; expand(`if`(n=0, 1, add(
           b(n-j)*binomial(n-1, j-1), j=1..min(3, n))*x))
        end:
    T:= (n, k)-> coeff(b(k), x, n):
    seq(seq(T(n, k), k=n..3*n), n=0..6);  # Alois P. Heinz, May 31 2018
  • Mathematica
    b[n_] := b[n] = Expand[If[n == 0, 1, Sum[b[n - j]*Binomial[n - 1, j - 1], {j, 1, Min[3, n]}]*x]];
    T[n_, k_] := Coefficient[b[k], x, n];
    Table[T[n, k], {n, 0, 6}, { k, n, 3n}] // Flatten (* Jean-François Alcover, Jul 10 2018, after Alois P. Heinz *)

A281901 Number of scenarios in the Gift Exchange Game with n players and n wrapped gifts when a gift can be stolen at most n times.

Original entry on oeis.org

1, 2, 31, 18252, 1495388159, 34155922905682979, 350521520018942991464535019, 2371013832433361706367594400829713564440, 14584126149704606223764458141727351569547933381159988406, 107640669875812795238625627484701500354901860426640161278022882392148747562
Offset: 0

Views

Author

Alois P. Heinz, Feb 01 2017

Keywords

Comments

Also total number of partitions of [k] into exactly n nonempty blocks, each of size at most n+1, for any k in the range n <= k <= n^2+n.

Crossrefs

Programs

  • Maple
    with(combinat):
    b:= proc(n, i, t) option remember; `if`(t*i add(b(j, n+1, n), j=0..(n+1)*n):
    seq(a(n), n=0..10);
  • Mathematica
    multinomial[n_, k_List] := n!/Times @@ (k!); b[n_, i_, t_] := b[n, i, t] = If[t*iJean-François Alcover, Mar 13 2017, translated from Maple *)

Formula

a(n) = A144510(n+1,n) = A144512(n,n).

A144626 Tetrahedron of numbers T(i,j,k) = (i+2*j+3*k)!/(i!*j!*k!*2^j*6^k) read with entries in the order defined in A144625.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 3, 4, 10, 10, 1, 6, 15, 15, 10, 60, 105, 70, 280, 280, 1, 10, 45, 105, 105, 20, 210, 840, 1260, 280, 2520, 6300, 2800, 15400, 15400, 1, 15, 105, 420, 945, 945, 35, 560, 3780, 12600, 17325, 840, 12600, 69300, 138600, 15400, 184800, 600600, 200200, 1401400, 1401400
Offset: 0

Views

Author

N. J. A. Sloane, Jan 18 2009, Jan 19 2009

Keywords

Comments

The slice sums are given by A144416.

Examples

			The n-th slice of the tetrahedrom consists of the terms T(i,j,k) with i+j+k = n.
Slices 0,1,2,3,4,5 are:
....................1
------------------
....................1
...................1.1
------------------
....................10
...................4.10
..................1.3..3
------------------
...................280
..................70.280
................10.60.105
...............1..6.15..15
------------------
..................15400
................2800.15400
...............280.2520.6300
.............20..210.840.1260
............1..10..45..105.105
------------------
.................1401400
.............200200.1401400
.........15400.184800...600600
......840..12600..69300...138600
...35....560....3780....12600...17325
1......15....105....420......945.....945
		

Crossrefs

A308363 a(n) = (1/n!) * Sum_{i_1=1..3} Sum_{i_2=1..3} ... Sum_{i_n=1..3} (-1)^(i_1 + i_2 + ... + i_n) * multinomial(i_1 + i_2 + ... + i_n; i_1, i_2, ..., i_n).

Original entry on oeis.org

1, -1, 5, -120, 6286, -557991, 74741031, -14055359935, 3529670102365, -1140712320228976, 461095707510195836, -227895625979289345441, 135204234793000554759865, -94817763471081620680039785, 77590302489065260867070145321, -73270395178157034753637372218736
Offset: 0

Views

Author

Seiichi Manyama, May 22 2019

Keywords

Examples

			a(2) = (1/2) * (binomial(1+1,1) - binomial(1+2,2) + binomial(1+3,3) - binomial(2+1,1) + binomial(2+2,2) - binomial(2+3,3) + binomial(3+1,1) - binomial(3+2,2) + binomial(3+3,3)) = 5.
		

Crossrefs

Row n=3 of A308356.
Cf. A144416.

Programs

  • PARI
    {a(n) = sum(i=n, 3*n, (-1)^i*i!*polcoef(sum(j=1, 3, x^j/j!)^n, i))/n!}

A192012 Number of ways to use the elements of set {1,..,k}, 0<=k<=3*n, once each to form a collection of n (possibly empty) sets, each with at most 3 elements.

Original entry on oeis.org

1, 4, 35, 877, 46173, 4108044, 550917287, 103674052788, 26046619272535, 8420151470990221, 3404266960229749907, 1682802564587905472500, 998472258682783813839141, 700281698972322460184258208, 573086115189070229131370358179, 541208343386984031504989621465925
Offset: 0

Views

Author

Adi Dani, Jun 22 2011

Keywords

Comments

Number of partitions of the set {0,1,...,3*n} into n parts of size <=3.

Examples

			a(0) = 1 = card({[e]}) where e denotes the empty set.
a(1) = 4 = card({[e],[1],[12],[123]}).
a(2) = 35 = card({ [e,e],[e,1],[e,12],[1,2],[e,123],[1,23],[2,13],[3,12],
[1,234],[2,134],[3,124],[4,123],[12,34],[13,24],[14,23],[12,345],[13,245],[14,235],[15,324],[23,145],[24,135],[25,134],[34,125],[35,124],[45,123],
[123,456],[124,356],[125,346],[126,345],[134,256],[135,246],[136,245],[145,236],[146,235],[156,234] }).
		

Crossrefs

Partial sums of A144416.

Programs

  • Mathematica
    Table[Sum[k!/(i!3^(i - j)2^(k + j - 2i))Binomial[i, j] Binomial[j,k + 2j - 3i], {k, 0, 3n}, {i, 0, n}, {j, 0, 3i - k}], {n, 0, 15}]

Formula

a(n) = Sum_{k=0..3*n} Sum_{i=0..n} Sum_{j=0..3*i-k} k! *C(i,j) *C(j,k+2*j-3*i) / (i! * 3^(i-j) * 2^(k+j-2*i) ).
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