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 1-7 of 7 results.

A144660 a(n) = Sum_{i=0..n} Sum_{j=0..n} Sum_{k=0..n} (i+j+k)!/(i!*j!*k!).

Original entry on oeis.org

1, 16, 271, 5248, 110251, 2435200, 55621567, 1301226496, 30992872483, 748574130016, 18283414868863, 450657134765056, 11192820128307871, 279787295456009728, 7032532242167190271, 177611430242835570688, 4504491083159761986451, 114662734697313744041248
Offset: 0

Views

Author

N. J. A. Sloane, Jan 31 2009, Feb 01 2009

Keywords

Crossrefs

Cf. A030662, A144661, A307318. This sum is very close to that in A144511.

Programs

  • Maple
    f:=n->add( add( add( (i+j+k)!/(i!*j!*k!), i=0..n),j=0..n),k=0..n); [seq(f(n),n=0..20)];
  • Mathematica
    Table[Sum[(i + j + k)!/(i!*j!*k!), {i, 0, n}, {j, 0, n}, {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Apr 02 2019 *)
    Table[Sum[(1 + k + 2*n)! * HypergeometricPFQ[{1, -1 - k - n, -n}, {-1 - k - 2*n, -k - n}, 1] / ((1 + k + n)*k!*n!^2), {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Apr 04 2019 *)
  • PARI
    {a(n) = sum(i=0, n, sum(j=0, n, sum(k=0, n, (i+j+k)!/(i!*j!*k!))))} \\ Seiichi Manyama, Apr 02 2019

Formula

From Vaclav Kotesovec, Apr 02 2019: (Start)
Recurrence: n^2*(2*n + 1)*(91*n^4 - 478*n^3 + 917*n^2 - 755*n + 222)*a(n) = 3*(2*n - 3)*(3*n - 5)*(3*n - 4)*(91*n^4 - 114*n^3 + 29*n^2 + 9*n - 3)*a(n-1) + n^2*(2*n + 1)*(91*n^4 - 478*n^3 + 917*n^2 - 755*n + 222)*a(n-2) - 3*(2*n - 3)*(3*n - 5)*(3*n - 4)*(91*n^4 - 114*n^3 + 29*n^2 + 9*n - 3)*a(n-3).
a(n) ~ 3^(3*n + 7/2) / (16*Pi*n). (End)

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 *)

A307350 a(n) = -Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} (-1)^(i+j+k) * (i+j+k)!/(3!*i!*j!*k!).

Original entry on oeis.org

0, 1, -5, 120, -2380, 52556, -1192625, 27798310, -660128942, 15907062666, -387785597485, 9543399745815, -236715891871160, 5910596888393926, -148421725618783545, 3745355227481531010, -94917946415633366050, 2414582011729590475886
Offset: 0

Views

Author

Seiichi Manyama, Apr 03 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Table[-Sum[Sum[Sum[(-1)^(i + j + k)*(i + j + k)!/(3!*i!*j!*k!), {i, 1, n}], {j, 1, n}], {k, 1, n}], {n, 0, 17}] (* Amiram Eldar, Apr 03 2019 *)
  • PARI
    {a(n) = -sum(i=1, n, sum(j=1, n, sum(k=1, n, (-1)^(i+j+k)*(i+j+k)!/(6*i!*j!*k!))))}
    
  • PARI
    {a(n) = -sum(i=3, 3*n, (-1)^i*i!*polcoef(sum(j=1, n, x^j/j!)^3, i))/6} \\ Seiichi Manyama, May 20 2019

Formula

a(n) ~ -(-1)^n * 3^(3*n + 5/2) / (256*Pi*n). - Vaclav Kotesovec, Apr 04 2019

A144658 a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} (i+j+k)!/(i!*j!*k!).

Original entry on oeis.org

0, 6, 222, 5052, 109512, 2432448, 55611294, 1301187912, 30992726652, 748573575780, 18283412752602, 450657126652626, 11192820097106112, 279787295335659972, 7032532241701837758, 177611430241032329568
Offset: 0

Views

Author

N. J. A. Sloane, Jan 30 2009

Keywords

Crossrefs

Cf. A144511.

Programs

  • Mathematica
    Table[Sum[Sum[Sum[(i+j+k)!/i!/j!/k!,{i,1,n}],{j,1,n}],{k,1,n}],{n,1,30}]
  • PARI
    {a(n) = sum(i=1, n, sum(j=1, n, sum(k=1, n, (i+j+k)!/(i!*j!*k!))))} \\ Seiichi Manyama, May 19 2019
    
  • PARI
    {a(n) = sum(i=3, 3*n, i!*polcoef(sum(j=1, n, x^j/j!)^3, i))} \\ Seiichi Manyama, May 19 2019

A147984 Column 5 of A144512.

Original entry on oeis.org

1, 2431, 4061871, 7528988476, 15467641899285, 34155922905682979, 79397199549271412737, 191739533381111401455478, 476872353039366288373555323
Offset: 0

Views

Author

N. J. A. Sloane, May 13 2009

Keywords

Crossrefs

A307353 a(n) = Sum_{1<=i<=j<=k<=n} (i+j+k)!/(i!*j!*k!).

Original entry on oeis.org

0, 6, 138, 2808, 59083, 1298797, 29538183, 688783509, 16365391557, 394523905488, 9621386549905, 236859066714283, 5876752842394018, 146774130963028054, 3686474939155802036, 93044751867415156290, 2358431594463240429469
Offset: 0

Views

Author

Seiichi Manyama, Apr 03 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[Sum[Sum[(i+j+k)!/(i!*j!*k!), {i, 1, j}], {j, 1, k}], {k, 1, n}], {n, 0, 20}] (* Vaclav Kotesovec, Apr 04 2019 *)
  • PARI
    {a(n) = sum(i=1, n, sum(j=i, n, sum(k=j, n, (i+j+k)!/(i!*j!*k!))))}

Formula

a(n) ~ 3^(3*n + 13/2) / (832*Pi*n). - Vaclav Kotesovec, Apr 04 2019
Showing 1-7 of 7 results.