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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A327388 Number of colored integer partitions of n such that ten colors are used and parts differ by size or by color.

Original entry on oeis.org

1, 10, 65, 320, 1320, 4762, 15500, 46410, 129710, 341990, 857695, 2059430, 4759235, 10630810, 23034880, 48562378, 99866045, 200766810, 395317950, 763661010, 1449390299, 2706189810, 4976391015, 9021860260, 16139848000, 28515535112, 49792637480, 85989053350
Offset: 10

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Author

Alois P. Heinz, Sep 03 2019

Keywords

Comments

In general, column k > 0 of A308680 is asymptotic to exp(Pi*sqrt(k*n/3)) * k^(1/4) / (3^(1/4) * 2^((k+3)/2) * n^(3/4)). - Vaclav Kotesovec, Sep 16 2019

Crossrefs

Column k=10 of A308680.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0, add((t->
          b(t, min(t, i-1), k)*binomial(k, j))(n-i*j), j=0..min(k, n/i))))
        end:
    a:= n-> (k-> add(b(n$2, k-i)*(-1)^i*binomial(k, i), i=0..k))(10):
    seq(a(n), n=10..45);
  • Mathematica
    A327388[n_] := SeriesCoefficient[(Product[(1 + x^k), {k, 1, n}] - 1)^10, {x, 0, n}]; Table[A327388[n], {n, 10, 37}] (* Robert P. P. McKone, Jan 31 2021 *)

Formula

a(n) ~ exp(Pi*sqrt(10*n/3)) * 5^(1/4) / (2^(25/4) * 3^(1/4) * n^(3/4)). - Vaclav Kotesovec, Sep 16 2019
G.f.: (-1 + Product_{k>=1} (1 + x^k))^10. - Ilya Gutkovskiy, Jan 31 2021

A327380 Number of colored integer partitions of n such that two colors are used and parts differ by size or by color.

Original entry on oeis.org

1, 2, 5, 8, 14, 22, 34, 50, 73, 104, 146, 202, 275, 372, 498, 660, 868, 1134, 1470, 1896, 2430, 3098, 3931, 4964, 6240, 7814, 9746, 12110, 14997, 18510, 22772, 27934, 34166, 41672, 50698, 61520, 74470, 89940, 108378, 130312, 156364, 187244, 223785, 266962
Offset: 2

Views

Author

Alois P. Heinz, Sep 03 2019

Keywords

Comments

With offset 0 convolution square of A000009(k+1). - George Beck, Jan 28 2021

Examples

			a(4) = 5: 2a1a1b, 2b1a1b, 2a2b, 3a1b, 3b1a.
a(5) = 8: 2a2b1a, 2a2b1b, 3a1a1b, 3b1a1b, 3a2b, 3b2a, 4a1b, 4b1a.
		

Crossrefs

Column k=2 of A308680.
Cf. A000009.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0, add((t->
          b(t, min(t, i-1), k)*binomial(k, j))(n-i*j), j=0..min(k, n/i))))
        end:
    a:= n-> (k-> add(b(n$2, k-i)*(-1)^i*binomial(k, i), i=0..k))(2):
    seq(a(n), n=2..45);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i < 1, 0, Sum[Function[t, b[t, Min[t, i - 1], k]*Binomial[k, j]][n - i*j], {j, 0, Min[k, n/i]}]]];
    a[n_] := With[{k = 2}, Sum[b[n, n, k-i]*(-1)^i*Binomial[k, i], {i, 0, k}]];
    a /@ Range[2, 45] (* Jean-François Alcover, May 06 2020, after Maple *)

Formula

a(n) ~ exp(Pi*sqrt(2*n/3)) / (2^(9/4) * 3^(1/4) * n^(3/4)). - Vaclav Kotesovec, Sep 14 2019
G.f.: (-1 + Product_{j>=1} (1 + x^j))^2. - Alois P. Heinz, Jan 29 2021

A341279 Triangle read by rows: T(n,k) = coefficient of x^n in expansion of (-1 + Product_{j>=1} 1 / (1 + (-x)^j))^k, n >= 0, 0 <= k <= n.

Original entry on oeis.org

1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 2, 0, 1, 0, 1, 2, 3, 0, 1, 0, 1, 3, 3, 4, 0, 1, 0, 1, 4, 6, 4, 5, 0, 1, 0, 2, 5, 9, 10, 5, 6, 0, 1, 0, 2, 8, 13, 16, 15, 6, 7, 0, 1, 0, 2, 9, 21, 26, 25, 21, 7, 8, 0, 1, 0, 2, 12, 27, 44, 45, 36, 28, 8, 9, 0, 1, 0, 3, 15, 40, 63, 80, 71, 49, 36, 9, 10, 0, 1
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 08 2021

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  0,  1;
  0,  0,  1;
  0,  1,  0,  1;
  0,  1,  2,  0,  1;
  0,  1,  2,  3,  0,  1;
  0,  1,  3,  3,  4,  0,  1;
  0,  1,  4,  6,  4,  5,  0,  1;
  0,  2,  5,  9, 10,  5,  6,  0,  1;
  0,  2,  8, 13, 16, 15,  6,  7,  0,  1;
  0,  2,  9, 21, 26, 25, 21,  7,  8,  0,  1;
  0,  2, 12, 27, 44, 45, 36, 28,  8,  9,  0,  1;
  ...
		

Crossrefs

Main diagonal and lower diagonals give A000012, A000004, A001477, A000217, A000290.
Row sums give A307058.
T(2n,n) gives A341265.

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([0, d, -d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    T:= proc(n, k) option remember;
          `if`(k=0, `if`(n=0, 1, 0), `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(T(j, q)*T(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    seq(seq(T(n, k), k=0..n), n=0..12);  # Alois P. Heinz, Feb 09 2021
  • Mathematica
    T[n_, k_] := SeriesCoefficient[(-1 + 2/QPochhammer[-1, -x])^k, {x, 0, n}]; Table[T[n, k], {n, 0, 12}, {k, 0, n}] // Flatten

Formula

G.f. of column k: (-1 + Product_{j>=1} (1 + x^(2*j-1)))^k.
Sum_{k=0..n} (-1)^(n-k) * T(n,k) = A000009(n).

A325915 Total number of colors used in all colored integer partitions of n where all colors from an initial interval of the color palette are used and parts differ by size or by color.

Original entry on oeis.org

0, 1, 3, 9, 25, 67, 176, 453, 1149, 2882, 7161, 17654, 43238, 105303, 255210, 615896, 1480771, 3548313, 8477415, 20199596, 48014369, 113879450, 269555798, 636875077, 1502195104, 3537705916, 8319377813, 19537936874, 45827441193, 107366261405, 251268532266
Offset: 0

Views

Author

Alois P. Heinz, Sep 08 2019

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1, add(b(n-j)*add(
         `if`(d::odd, d, 0), d=numtheory[divisors](j)), j=1..n)/n)
        end:
    g:= proc(n) option remember; `if`(n=0, [1, 0],
          (p-> p+[0, p[1]])(add(b(j)*g(n-j), j=1..n)))
        end:
    a:= n-> g(n)[2]:
    seq(a(n), n=0..32);
  • Mathematica
    b[n_] := b[n] = If[n == 0, 1, Sum[b[n - j] Sum[If[OddQ[d], d, 0], {d, Divisors[j]}], {j, 1, n}]/n];
    g[n_] := g[n] = If[n == 0, {1, 0}, Function[p, p + {0, p[[1]]}][Sum[b[j] g[n - j], {j, 1, n}]]];
    a[n_] := g[n][[2]];
    a /@ Range[0, 32] (* Jean-François Alcover, Dec 09 2020, after Alois P. Heinz *)

Formula

a(n) = Sum_{k=1..n} k * A308680(n,k).
a(n) ~ c * d^n * n, where d = 2.26562663992642295791262530033324290454663... is the root of the equation QPochhammer[-1, 1/d] = 4 and c = 0.1771510533646387556482103930322780317974659818141571819... - Vaclav Kotesovec, Sep 18 2019
Previous Showing 11-14 of 14 results.