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 13 results. Next

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).

A320545 Number of partitions of n into parts of exactly three sorts which are introduced in ascending order such that sorts of adjacent parts are different.

Original entry on oeis.org

1, 4, 12, 31, 73, 165, 357, 760, 1582, 3270, 6678, 13589, 27482, 55468, 111588, 224259, 449908, 902106, 1807173, 3619162, 7244557, 14499238, 29011551, 58044194, 116115782, 232275383, 464607730, 929306306, 1858730674, 3717648658, 7435541392, 14871467784
Offset: 3

Views

Author

Alois P. Heinz, Oct 15 2018

Keywords

Crossrefs

Column k=3 of A262495.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, k^(n-1),
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k)))
        end:
    A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, k*b(n$2, k-1))):
    a:= n-> (k-> add(A(n, k-i)*(-1)^i/(i!*(k-i)!), i=0..k))(3):
    seq(a(n), n=3..40);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i == 1, k^(n - 1), b[n, i - 1, k] + If[i > n, 0, k b[n - i, i, k]]];
    A[n_, k_] := If[n == 0, 1, If[k < 2, k, k b[n, n, k - 1]]];
    a[n_] := With[{k = 3}, Sum[A[n, k - i] (-1)^i/(i! (k - i)!), {i, 0, k}]];
    a /@ Range[3, 40] (* Jean-François Alcover, Dec 08 2020, after Alois P. Heinz *)

Formula

a(n) ~ 2^(n-2) / QPochhammer[1/2]. - Vaclav Kotesovec, Oct 25 2018

A262445 Number of exact 3-colored partitions such that no adjacent parts have the same color.

Original entry on oeis.org

0, 0, 0, 6, 24, 72, 186, 438, 990, 2142, 4560, 9492, 19620, 40068, 81534, 164892, 332808, 669528, 1345554, 2699448, 5412636, 10843038, 21714972, 43467342, 86995428, 174069306, 348265164, 696694692, 1393652298, 2787646380, 5575837836, 11152384044, 22305891948, 44613248352, 89228806704, 178460625402, 356925987924
Offset: 0

Views

Author

Ran Pan, Sep 23 2015

Keywords

Comments

a(1) = a(2) = 0 because we need to use exactly three colors, which means the number of parts should be greater than two.
All terms are multiples of 6.

Examples

			a(3)=6 because there are three partitions of 3 and there are no ways to color [3] or [2,1] but there are six ways to color [1,1,1].
		

Crossrefs

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:
    a:= n-> `if`(n=0, 0, b(n$2, 2)/2*3-6*b(n$2, 1)+3):
    seq(a(n), n=0..40);  # Alois P. Heinz, Sep 23 2015
  • 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]]]]; a[n_] := If[n == 0, 0, b[n, n, 2]/2*3 - 6*b[n, n, 1] + 3]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Feb 07 2017, after Alois P. Heinz *)

Formula

G.f.: 3/2*Product_{k>=1} (1/(1-2*x^k)) - 6*Product_{k>=1} (1/(1-x^k)) + 3/(1-x) + 3/2.
a(n) = A262444(n) - 6*A000041(n) + 3, for n >= 1.
a(n) = 6 * A262495(n,3). - Alois P. Heinz, Sep 24 2015

A262496 Number of partitions of n into parts of sorts {1, 2, ... } which are introduced in ascending order such that sorts of adjacent parts are different.

Original entry on oeis.org

1, 1, 2, 4, 10, 27, 87, 312, 1269, 5703, 28082, 149643, 855938, 5217753, 33712046, 229799508, 1646314498, 12355371024, 96861186897, 791258791159, 6720627161903, 59234364141343, 540812222291531, 5106663817387466, 49798678281320763, 500857393909589995
Offset: 0

Views

Author

Alois P. Heinz, Sep 24 2015

Keywords

Examples

			a(3) = 4: 3a, 2a1b, 1a1b1a, 1a1b1c (in this example the sorts are labeled a, b, c).
		

Crossrefs

Row sums of A262495.
Cf. A258466.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, k^(n-1),
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k)))
        end:
    A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, k*b(n$2, k-1))):
    T:= (n, k)->  add(A(n, k-i)*(-1)^i/(i!*(k-i)!), i=0..k):
    a:= n-> add(T(n, k), k=0..n):
    seq(a(n), n=0..30);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n==0 || i==1, k^(n-1), b[n, i-1, k] + If[i > n, 0, k*b[n-i, i, k]]]; A[n_, k_] := If[n==0, 1, If[k<2, k, k*b[n, n, k - 1]]]; T[n_, k_] := Sum[A[n, k-i]*(-1)^i/(i!*(k-i)!), {i, 0, k}]; a[n_] := Sum[T[n, k], {k, 0, n}]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Feb 05 2017, translated from Maple *)

A320546 Number of partitions of n into parts of exactly four sorts which are introduced in ascending order such that sorts of adjacent parts are different.

Original entry on oeis.org

1, 7, 33, 130, 464, 1558, 5039, 15886, 49282, 151165, 460352, 1394863, 4212752, 12694566, 38197710, 114820403, 344919283, 1035670246, 3108844526, 9330186438, 27997888759, 84008273161, 252054096569, 756220672185, 2268778953179, 6806570182252, 20420177671614
Offset: 4

Views

Author

Alois P. Heinz, Oct 15 2018

Keywords

Crossrefs

Column k=4 of A262495.
Cf. A258459.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, k^(n-1),
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k)))
        end:
    A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, k*b(n$2, k-1))):
    a:= n-> (k-> add(A(n, k-i)*(-1)^i/(i!*(k-i)!), i=0..k))(4):
    seq(a(n), n=4..40);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i == 1, k^(n - 1), b[n, i - 1, k] + If[i > n, 0, k b[n - i, i, k]]];
    A[n_, k_] := If[n == 0, 1, If[k < 2, k, k b[n, n, k - 1]]];
    a[n_] := With[{k = 4}, Sum[A[n, k - i] (-1)^i/(i! (k - i)!), {i, 0, k}]];
    a /@ Range[4, 40] (* Jean-François Alcover, Dec 08 2020, after Alois P. Heinz *)

Formula

a(n) ~ 3^(n-1) / (3! * QPochhammer[1/3]). - Vaclav Kotesovec, Oct 25 2018

A320547 Number of partitions of n into parts of exactly five sorts which are introduced in ascending order such that sorts of adjacent parts are different.

Original entry on oeis.org

1, 11, 77, 438, 2216, 10423, 46732, 202826, 860599, 3593651, 14835058, 60735635, 247155920, 1001321100, 4043485479, 16288776186, 65500040622, 263035896496, 1055252507399, 4230340498375, 16949360224358, 67881450386237, 271777857121332, 1087867654290457
Offset: 5

Views

Author

Alois P. Heinz, Oct 15 2018

Keywords

Crossrefs

Column k=5 of A262495.
Cf. A258460.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, k^(n-1),
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k)))
        end:
    A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, k*b(n$2, k-1))):
    a:= n-> (k-> add(A(n, k-i)*(-1)^i/(i!*(k-i)!), i=0..k))(5):
    seq(a(n), n=5..40);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i == 1, k^(n - 1), b[n, i - 1, k] + If[i > n, 0, k b[n - i, i, k]]];
    A[n_, k_] := If[n == 0, 1, If[k < 2, k, k b[n, n, k - 1]]];
    a[n_] := With[{k = 5}, Sum[A[n, k - i] (-1)^i/(i! (k - i)!), {i, 0, k}]];
    a /@ Range[5, 40] (* Jean-François Alcover, Dec 08 2020, after Alois P. Heinz *)

Formula

a(n) ~ 4^(n-1) / (4! * QPochhammer[1/4]). - Vaclav Kotesovec, Oct 25 2018

A320548 Number of partitions of n into parts of exactly six sorts which are introduced in ascending order such that sorts of adjacent parts are different.

Original entry on oeis.org

1, 16, 157, 1223, 8331, 52078, 307123, 1738442, 9552826, 51357799, 271624228, 1418856967, 7341442171, 37708533544, 192586163135, 979219603193, 4961598120154, 25071026570558, 126410385741982, 636282269651863, 3198360710675384, 16059685006324807
Offset: 6

Views

Author

Alois P. Heinz, Oct 15 2018

Keywords

Crossrefs

Column k=6 of A262495.
Cf. A258461.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, k^(n-1),
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k)))
        end:
    A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, k*b(n$2, k-1))):
    a:= n-> (k-> add(A(n, k-i)*(-1)^i/(i!*(k-i)!), i=0..k))(6):
    seq(a(n), n=6..40);

Formula

a(n) ~ 5^(n-1) / (5! * QPochhammer[1/5]). - Vaclav Kotesovec, Oct 25 2018

A320549 Number of partitions of n into parts of exactly seven sorts which are introduced in ascending order such that sorts of adjacent parts are different.

Original entry on oeis.org

1, 22, 289, 2957, 26073, 208516, 1558219, 11087757, 76079369, 507834036, 3318628468, 21330628088, 135325211035, 849659803048, 5290544985029, 32722489543068, 201296535411532, 1232850239281547, 7523511821702402, 45777353201698899, 277862479922939524
Offset: 7

Views

Author

Alois P. Heinz, Oct 15 2018

Keywords

Crossrefs

Column k=7 of A262495.
Cf. A258462.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, k^(n-1),
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k)))
        end:
    A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, k*b(n$2, k-1))):
    a:= n-> (k-> add(A(n, k-i)*(-1)^i/(i!*(k-i)!), i=0..k))(7):
    seq(a(n), n=7..40);

Formula

a(n) ~ 6^(n-1) / (6! * QPochhammer[1/6]). - Vaclav Kotesovec, Oct 25 2018

A320550 Number of partitions of n into parts of exactly eight sorts which are introduced in ascending order such that sorts of adjacent parts are different.

Original entry on oeis.org

1, 29, 492, 6401, 70880, 704676, 6490951, 56524414, 471750268, 3810085913, 29989229889, 231255237342, 1754111872952, 13128442914265, 97189645391839, 713050007293418, 5192646586543845, 37581376345173772, 270593146238709314, 1939929376873532436
Offset: 8

Views

Author

Alois P. Heinz, Oct 15 2018

Keywords

Crossrefs

Column k=8 of A262495.
Cf. A258463.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, k^(n-1),
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k)))
        end:
    A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, k*b(n$2, k-1))):
    a:= n-> (k-> add(A(n, k-i)*(-1)^i/(i!*(k-i)!), i=0..k))(8):
    seq(a(n), n=8..40);

Formula

a(n) ~ 7^(n-1) / (7! * QPochhammer[1/7]). - Vaclav Kotesovec, Oct 25 2018

A320551 Number of partitions of n into parts of exactly nine sorts which are introduced in ascending order such that sorts of adjacent parts are different.

Original entry on oeis.org

1, 37, 788, 12705, 172520, 2084836, 23169639, 241881526, 2406802476, 23064505722, 214505275666, 1947297442708, 17332491414655, 151788374232332, 1311496639251360, 11205023121317869, 94832831557101194, 796244028802170279, 6640545376656272033
Offset: 9

Views

Author

Alois P. Heinz, Oct 15 2018

Keywords

Crossrefs

Column k=9 of A262495.
Cf. A258464.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i=1, k^(n-1),
          b(n, i-1, k) +`if`(i>n, 0, k*b(n-i, i, k)))
        end:
    A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, k*b(n$2, k-1))):
    a:= n-> (k-> add(A(n, k-i)*(-1)^i/(i!*(k-i)!), i=0..k))(9):
    seq(a(n), n=9..40);

Formula

a(n) ~ 8^(n-1) / (8! * QPochhammer[1/8]). - Vaclav Kotesovec, Oct 25 2018
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