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 1-4 of 4 results.

A256130 Number T(n,k) of partitions of n into parts of exactly k sorts which are introduced in ascending order; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 2, 1, 0, 3, 4, 1, 0, 5, 12, 7, 1, 0, 7, 30, 33, 11, 1, 0, 11, 72, 130, 77, 16, 1, 0, 15, 160, 463, 438, 157, 22, 1, 0, 22, 351, 1557, 2216, 1223, 289, 29, 1, 0, 30, 743, 5031, 10422, 8331, 2957, 492, 37, 1, 0, 42, 1561, 15877, 46731, 52078, 26073, 6401, 788, 46, 1
Offset: 0

Views

Author

Alois P. Heinz, Mar 15 2015

Keywords

Comments

In general, column k>1 is asymptotic to c*k^n, where c = 1/(k!*Product_{n>=1} (1-1/k^n)) = 1/(k!*QPochhammer[1/k, 1/k]). - Vaclav Kotesovec, Jun 01 2015

Examples

			T(3,1) = 3: 1a1a1a, 2a1a, 3a.
T(3,2) = 4: 1a1a1b, 1a1b1a, 1a1b1b, 2a1b.
T(3,3) = 1: 1a1b1c.
Triangle T(n,k) begins:
  1;
  0,  1;
  0,  2,    1;
  0,  3,    4,     1;
  0,  5,   12,     7,     1;
  0,  7,   30,    33,    11,     1;
  0, 11,   72,   130,    77,    16,     1;
  0, 15,  160,   463,   438,   157,    22,    1;
  0, 22,  351,  1557,  2216,  1223,   289,   29,   1;
  0, 30,  743,  5031, 10422,  8331,  2957,  492,  37,  1;
  0, 42, 1561, 15877, 46731, 52078, 26073, 6401, 788, 46,  1;
  ...
		

Crossrefs

Columns k=0-10 give: A000007, A000041 (for n>0), A258457, A258458, A258459, A258460, A258461, A258462, A258463, A258464, A258465.
Row sums give A258466.
T(2n,n) give A258467.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k))))
        end:
    T:= (n, k)-> add(b(n$2, k-i)*(-1)^i/(i!*(k-i)!), i=0..k):
    seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n==0, 1, If[i<1, 0, b[n, i-1, k] + If[i>n, 0, k*b[n-i, i, k]]]]; T[n_, k_] := Sum[b[n, n, k-i]*(-1)^i/(i!*(k-i)!), {i, 0, k}]; Table[Table[T[n, k], {k, 0, n}], {n, 0, 10}] // Flatten (* Jean-François Alcover, Feb 21 2016, after Alois P. Heinz *)

Formula

T(n,k) = A255970(n,k)/k! = (Sum_{i=0..k} (-1)^i * C(k,i) * A246935(n,k-i)) / A000142(k).

A319600 Number T(n,k) of plane partitions of n into parts of exactly k sorts; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 3, 4, 0, 6, 22, 18, 0, 13, 96, 198, 120, 0, 24, 330, 1272, 1800, 840, 0, 48, 1146, 7518, 19152, 20640, 7920, 0, 86, 3518, 36684, 148200, 274080, 234720, 75600, 0, 160, 10946, 177438, 1080960, 3083640, 4462560, 3180240, 887040, 0, 282, 32102, 788928, 6952440, 28621920, 62056080, 73175760, 44432640, 10886400
Offset: 0

Views

Author

Alois P. Heinz, Sep 24 2018

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  0,   1;
  0,   3,     4;
  0,   6,    22,     18;
  0,  13,    96,    198,     120;
  0,  24,   330,   1272,    1800,     840;
  0,  48,  1146,   7518,   19152,   20640,    7920;
  0,  86,  3518,  36684,  148200,  274080,  234720,   75600;
  0, 160, 10946, 177438, 1080960, 3083640, 4462560, 3180240, 887040;
  ...
		

Crossrefs

Columns k=0-1 give: A000007, A000219 (for n>0).
Row sums give A319601.
Main diagonal gives A053529.

Formula

T(n,k) = Sum_{i=0..k} (-1)^i * C(k,i) * A306100(n,k-i).
T(n,k) = k! * A319730(n,k).

A319731 Number of plane partitions of n into parts of sorts {1, 2, ... } which are introduced in ascending order.

Original entry on oeis.org

1, 1, 5, 20, 99, 483, 2855, 16759, 112794, 777862, 5864191, 45388575, 381557427, 3265488790, 29815712658, 279926300139, 2762328453142, 27952237049003, 296275051753578, 3212312177119572, 36258222471852860, 419025393587012853, 5010022284030897550
Offset: 0

Views

Author

Alois P. Heinz, Sep 26 2018

Keywords

Crossrefs

Row sums of A319730.
Cf. A258466.

Formula

a(n) = Sum_{k=0..n} A319730(n,k).

A319732 Number of plane partitions of 2n into parts of exactly n sorts which are introduced in ascending order.

Original entry on oeis.org

1, 3, 48, 1253, 45040, 2074266, 115308621, 7403931515, 542578637369, 44353623326199, 3992458392860603, 392255543503496555, 41726405940340028501, 4768006168373548992878, 582709500037368041005243, 75765509130126834789261446, 10436240655486571146294062847
Offset: 0

Views

Author

Alois P. Heinz, Sep 26 2018

Keywords

Crossrefs

Formula

a(n) = A319730(2n,n).
Showing 1-4 of 4 results.