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.

A363048 Triangle T(n,k), n >= 0, 0 <= k <= n, read by rows, where T(n,k) is the number of partitions of n whose greatest part is a multiple of k.

Original entry on oeis.org

1, 0, 1, 0, 2, 1, 0, 3, 1, 1, 0, 5, 3, 1, 1, 0, 7, 3, 2, 1, 1, 0, 11, 6, 4, 2, 1, 1, 0, 15, 7, 5, 3, 2, 1, 1, 0, 22, 12, 7, 6, 3, 2, 1, 1, 0, 30, 14, 11, 7, 5, 3, 2, 1, 1, 0, 42, 22, 14, 11, 8, 5, 3, 2, 1, 1, 0, 56, 27, 19, 14, 11, 7, 5, 3, 2, 1, 1, 0, 77, 40, 27, 21, 15, 12, 7, 5, 3, 2, 1, 1
Offset: 0

Views

Author

Seiichi Manyama, May 14 2023

Keywords

Examples

			Triangle begins:
  1;
  0,  1;
  0,  2,  1;
  0,  3,  1,  1;
  0,  5,  3,  1, 1;
  0,  7,  3,  2, 1, 1;
  0, 11,  6,  4, 2, 1, 1;
  0, 15,  7,  5, 3, 2, 1, 1;
  0, 22, 12,  7, 6, 3, 2, 1, 1;
  0, 30, 14, 11, 7, 5, 3, 2, 1, 1;
  ...
		

Crossrefs

Row sums give A323433.
Column k=0..5 give A000007, A000041, A027187, A363045, A363046, A363047.
T(2n,n) gives A052810.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1,
         `if`(i<1, 0, b(n, i-1)+b(n-i, min(n-i, i))))
        end:
    T:= (n, k)-> `if`(k=0, `if`(n=0, 1, 0), add(
        (j-> b(n-j, min(n-j, j)))(k*i), i=0..n/k)):
    seq(seq(T(n, k), k=0..n), n=0..12);  # Alois P. Heinz, May 14 2023
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, b[n, i - 1] + b[n - i, Min[n - i, i]]]];
    T[n_, k_] := If[k == 0, If[n == 0, 1, 0], Sum[Function[j, b[n - j, Min[n - j, j]]][k*i], {i, 0, n/k}]];
    Table[Table[T[n, k], {k, 0, n}], {n, 0, 12}] // Flatten (* Jean-François Alcover, Oct 20 2023, after Alois P. Heinz *)
  • PARI
    T(n, k) = sum(j=0, n, #partitions(n-k*j, k*j));

Formula

For k > 0, g.f. of column k: Sum_{i>=0} x^(k*i)/Product_{j=1..k*i} (1-x^j).

A363067 Number of partitions p of n such that (1/4)*max(p) is a part of p.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 2, 3, 5, 7, 10, 13, 18, 23, 31, 39, 51, 64, 81, 102, 128, 159, 198, 245, 304, 374, 460, 563, 689, 841, 1023, 1242, 1505, 1819, 2195, 2642, 3173, 3804, 4551, 5435, 6477, 7707, 9151, 10850, 12843, 15175, 17902, 21089, 24802, 29132, 34164, 40012, 46796, 54663, 63766
Offset: 0

Views

Author

Seiichi Manyama, May 16 2023

Keywords

Examples

			a(8) = 3 counts these partitions:  431, 4211, 41111.
		

Crossrefs

Programs

  • Mathematica
    nmax = 60; CoefficientList[Series[Sum[x^(5*k)/Product[1 - x^j, {j, 1, 4*k}], {k, 0, nmax}], {x, 0, nmax}], x]  (* Vaclav Kotesovec, Jun 18 2025 *)
    nmax = 60; p=1; s=1; Do[p=Expand[p*(1-x^(4*k))*(1-x^(4*k-1))*(1-x^(4*k-2))*(1-x^(4*k-3))]; p=Take[p, Min[nmax+1, Exponent[p, x]+1, Length[p]]]; s+=x^(5*k)/p; , {k, 1, nmax}]; CoefficientList[Series[s, {x, 0, nmax}], x] (* Vaclav Kotesovec, Jun 18 2025 *)
  • PARI
    a(n) = sum(k=0, n\5, #partitions(n-5*k, 4*k));

Formula

G.f.: Sum_{k>=0} x^(5*k)/Product_{j=1..4*k} (1-x^j).
a(n) ~ Gamma(1/4) * Pi^(1/4) * exp(Pi*sqrt(2*n/3)) / (2^(49/8) * 3^(5/8) * n^(9/8)). - Vaclav Kotesovec, Jun 19 2025

A363095 Number of partitions of n whose least part is a multiple of 4.

Original entry on oeis.org

0, 0, 0, 1, 0, 0, 0, 2, 1, 1, 1, 3, 2, 3, 3, 7, 6, 8, 9, 13, 13, 17, 19, 28, 30, 38, 43, 56, 62, 76, 87, 110, 124, 151, 173, 211, 241, 289, 332, 399, 456, 539, 620, 733, 838, 983, 1127, 1322, 1513, 1761, 2016, 2343, 2677, 3096, 3536, 4083, 4655, 5355, 6101, 7005, 7969, 9124, 10370, 11856, 13453, 15340
Offset: 1

Views

Author

Seiichi Manyama, May 19 2023

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 60; Rest[CoefficientList[Series[Sum[x^(4*k)/QPochhammer[x^(4*k), x], {k, 1, nmax/4}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, May 20 2023 *)
  • PARI
    my(N=70, x='x+O('x^N)); concat([0, 0, 0], Vec(sum(k=1, N, x^(4*k)/prod(j=4*k, N, 1-x^j))))

Formula

G.f.: Sum_{k>=1} x^(4*k)/Product_{j>=4*k} (1-x^j).
a(n) ~ Pi^3 * exp(Pi*sqrt(2*n/3)) / (3 * 2^(5/2) * n^(5/2)) * (1 - (5*sqrt(6)/Pi + 169*Pi*sqrt(6)/144)/sqrt(n)). - Vaclav Kotesovec, May 21 2023

A372703 Number of partitions of n into distinct parts such that number of parts is a multiples of 4.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 5, 6, 9, 11, 15, 18, 23, 27, 34, 39, 47, 54, 64, 72, 84, 94, 108, 120, 136, 150, 169, 185, 207, 226, 251, 273, 302, 328, 362, 393, 433, 470, 518, 563, 621, 677, 748, 818, 906, 994, 1104, 1216, 1354, 1497, 1671, 1853, 2073, 2305, 2582, 2877, 3226, 3599
Offset: 0

Views

Author

Seiichi Manyama, May 23 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=70, x='x+O('x^N)); Vec(sum(k=0, N, prod(j=1, 4*k, x^j/(1-x^j))))

Formula

G.f.: Sum_{k>=0} x^(2*k*(4*k+1)) / Product_{j=1..4*k} (1-x^j) = Sum_{k>=0} Product_{j=1..4*k} (x^j/(1-x^j)).
Showing 1-4 of 4 results.