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.

A147783 Number of partitions of n into parts divisible by 2 or 5.

Original entry on oeis.org

1, 0, 1, 0, 2, 1, 3, 1, 5, 2, 8, 3, 12, 5, 17, 9, 25, 13, 35, 19, 51, 28, 69, 40, 96, 59, 129, 81, 175, 113, 236, 154, 313, 210, 412, 286, 542, 381, 705, 506, 921, 668, 1185, 875, 1525, 1148, 1948, 1485, 2485, 1918, 3157, 2462, 3990, 3150
Offset: 0

Views

Author

Alexander E. Holroyd (holroyd at math.ubc.ca)

Keywords

Comments

Also number of partitions of n with no part and no difference between two parts equal to 1 or 3.
Also number of partitions of n with no part appearing 1 or 3 times.

Crossrefs

Programs

  • Mathematica
    nmax = 60; CoefficientList[Series[Product[(1 + x^(5*k))/(1 - x^(2*k)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 23 2015 *)

Formula

G.f.: Product_{k>=1} (1-x^(10k))/(1-x^(2k))/(1-x^(5k)).
a(n) ~ exp(sqrt(2*n/5)*Pi)/(4*sqrt(5)*n). - Vaclav Kotesovec, Sep 23 2015

A147784 Number of partitions of n into parts divisible by 3 or 4.

Original entry on oeis.org

1, 0, 0, 1, 1, 0, 2, 1, 2, 3, 2, 2, 7, 3, 4, 9, 9, 6, 15, 11, 15, 21, 19, 19, 39, 27, 32, 51, 51, 45, 78, 67, 82, 107, 104, 108, 172, 143, 165, 226, 232, 226, 328, 306, 356, 441, 446, 470, 655, 601, 677, 857, 891, 908, 1197, 1169, 1325, 1582
Offset: 0

Views

Author

Alexander E. Holroyd (holroyd at math.ubc.ca)

Keywords

Comments

Also number of partitions of n with no part and no difference between two parts equal to 1,2 or 5.
Also number of partitions of n with no part appearing 1,2 or 5 times.

Crossrefs

Programs

  • Mathematica
    nmax = 60; CoefficientList[Series[Product[(1 + x^(3*k))*(1 + x^(6*k))/(1 - x^(4*k)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 23 2015 *)

Formula

G.f.: Product_{k>=1} (1-x^(12k))/(1-x^(3k))/(1-x^(4k)).
a(n) ~ exp(sqrt(n/3)*Pi)/(4*sqrt(6)*n). - Vaclav Kotesovec, Sep 23 2015

A147785 Number of partitions of n into parts divisible by 3 or 5.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 2, 0, 1, 3, 2, 2, 5, 2, 3, 9, 4, 5, 13, 6, 11, 19, 10, 15, 28, 19, 23, 40, 27, 34, 63, 40, 50, 85, 59, 79, 121, 85, 109, 166, 132, 155, 230, 180, 216, 325, 255, 300, 436, 351, 429, 588, 485, 576, 789, 680, 784, 1050, 912, 1053, 1421, 1228
Offset: 0

Views

Author

Alexander E. Holroyd (holroyd at math.ubc.ca)

Keywords

Comments

Also number of partitions of n with no part and no difference between two parts equal to 1,2,4 or 7.
Also number of partitions of n with no part appearing 1,2,4 or 7 times.

Crossrefs

Programs

  • Maple
    with(numtheory):
    a:= proc(n) option remember; `if`(n=0, 1, add(add(
          `if`(irem(d, 3)=0 or irem(d, 5)=0, d, 0),
               d=divisors(j))*a(n-j), j=1..n)/n)
        end:
    seq(a(n), n=0..65);  # Alois P. Heinz, Dec 02 2016
  • Mathematica
    nmax = 60; CoefficientList[Series[Product[(1-x^(15*k))/((1-x^(3*k))*(1-x^(5*k))), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 23 2015 *)

Formula

G.f.: Product_{k>=1} (1-x^(15k)) / ((1-x^(3k))*(1-x^(5k))).
a(n) ~ sqrt(7/5) * exp(sqrt(14*n/5)*Pi/3) / (12*n). - Vaclav Kotesovec, Sep 23 2015

A147786 Number of partitions of n into parts divisible by 4 or 5.

Original entry on oeis.org

1, 0, 0, 0, 1, 1, 0, 0, 2, 1, 2, 0, 3, 2, 2, 3, 5, 3, 4, 3, 11, 5, 6, 6, 15, 13, 10, 9, 23, 17, 23, 15, 34, 27, 31, 33, 50, 40, 48, 45, 86, 60, 71, 69, 116, 106, 105, 102, 169, 144, 176, 150, 237, 211, 240, 248, 335, 299, 347, 338, 506, 425, 487, 487, 681
Offset: 0

Views

Author

Alexander E. Holroyd (holroyd at math.ubc.ca)

Keywords

Comments

Also number of partitions of n with no part and no difference between two parts equal to 1,2,3,6,7 or 11.
Also number of partitions of n with no part appearing 1,2,3,6,7 or 11 times.

Crossrefs

Programs

  • Mathematica
    nmax = 60; CoefficientList[Series[Product[(1 + x^(5*k))*(1 + x^(10*k))/(1 - x^(4*k)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 23 2015 *)

Formula

G.f.: Product_{k>=1} (1-x^(20k))/(1-x^(4k))/(1-x^(5k)).
a(n) ~ exp(2*Pi*sqrt(n/15))/(2*sqrt(30)*n). - Vaclav Kotesovec, Sep 23 2015
Showing 1-4 of 4 results.