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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A265251 Number of partitions of n such that there is exactly one part which occurs three times, while all other parts occur only once.

Original entry on oeis.org

0, 0, 0, 1, 0, 1, 2, 2, 2, 4, 6, 6, 9, 10, 14, 19, 22, 26, 35, 40, 50, 63, 74, 88, 107, 127, 150, 181, 213, 249, 296, 345, 401, 473, 546, 636, 741, 853, 983, 1138, 1306, 1498, 1722, 1967, 2247, 2574, 2925, 3327, 3788, 4294, 4866, 5516, 6233, 7036, 7947, 8953
Offset: 0

Views

Author

Emeric Deutsch, Dec 28 2015

Keywords

Comments

Conjecture: a(n) is also the difference between the number of parts in the distinct partitions of n and the number of distinct parts in the odd partitions of n (offset 0). For example, if n = 5, there are 5 parts in the distinct partitions of 5 (5, 41, 32) and 4 distinct parts in the odd partitions of 5 (namely, 5,3,1,1 in 5,311,11111) with difference 1. - George Beck, Apr 22 2017
George E. Andrews has kindly informed me that he has proved this conjecture and the result will be included in his article "Euler's Partition Identity and Two Problems of George Beck" which will appear in The Mathematics Student, 86, Nos. 1-2, January - June (2017). - George Beck, Apr 23 2017

Examples

			a(9) = 4 because we have [2,2,2,3], [3,3,3], [1,1,1,2,4], and [1,1,1,6].
		

Crossrefs

Column k=3 of A266477.

Programs

  • Maple
    g := add(x^(3*k)/(1+x^k), k = 1 .. 100)*mul(1+x^i, i = 1 .. 100): gser := series(g, x = 0, 80): seq(coeff(gser, x, m), m = 0 .. 75);
    # second Maple program:
    b:= proc(n, i, t) option remember; `if`(n>i*(i+5-4*t)/2, 0,
         `if`(n=0, t, b(n, i-1, t)+`if`(i>n, 0, b(n-i, i-1, t)+
         `if`(t=1 or 3*i>n, 0, b(n-3*i, i-1, 1)))))
        end:
    a:= n-> b(n$2, 0):
    seq(a(n), n=0..100);  # Alois P. Heinz, Dec 28 2015
  • Mathematica
    b[n_, i_, t_] := b[n, i, t] = If[n > i*(i + 5 - 4*t)/2, 0, If[n == 0, t, b[n, i - 1, t] + If[i > n, 0, b[n - i, i - 1, t] + If[t == 1 || 3*i > n, 0, b[n - 3*i, i - 1, 1]]]]]; a[n_] := b[n, n, 0]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Dec 11 2016, after Alois P. Heinz *)
    Take[ CoefficientList[ Expand[ Sum[x^(3k)/(1 + x^k), {k, 60}] Product[1 + x^i, {i, 60}]], x], 60] (* slower than above *) (* Robert G. Wilson v, Apr 24 2017 *)
  • PARI
    x='x + O('x^54); concat([0, 0, 0],Vec(sum(k=1, 54, x^(3*k)/(1 + x^k)* prod(i=1, 54, 1 + x^i)))) \\ Indranil Ghosh, Apr 24 2017

Formula

G.f.: Sum_{k>=1} x^{3k}/(1+x^k)*Product_{i>=1} (1+x^i).
a(n) ~ c * exp(Pi*sqrt(n/3)) / n^(1/4), where c = 3^(1/4) * (2*log(2) - 1) / (4*Pi) = 0.040456547528... - Vaclav Kotesovec, May 24 2018

A266480 Maximal product of multiplicities of parts of a partition of n.

Original entry on oeis.org

1, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 15, 18, 21, 24, 28, 32, 36, 40, 45, 50, 56, 64, 72, 84, 96, 108, 120, 135, 150, 165, 180, 200, 220, 240, 264, 288, 312, 336, 364, 405, 450, 495, 540, 600, 660, 720, 792, 864, 936, 1008, 1092, 1176, 1260, 1365, 1470, 1575
Offset: 0

Views

Author

Emeric Deutsch and Alois P. Heinz, Dec 29 2015

Keywords

Examples

			a(4) = 4 because the products of the multiplicities of the parts in the partitions [4], [1,3], [2,2], [1,1,2], [1,1,1,1] are 1, 1, 2, 2, 4, respectively.
a(21) = 7*4*2 = 56 for partition [1,1,1,1,1,1,1,2,2,2,2,3,3].
		

Crossrefs

Row lengths of A266477.
Cf. A266871.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0 or i=1, max(1, n),
          max(seq(b(n-i*j, i-1)*max(1, j), j=0..n/i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..100);
  • Mathematica
    Table[Max@ Map[Times @@ Map[Last, Tally@ #] &, IntegerPartitions@ n], {n, 0, 56}] (* Michael De Vlieger, Dec 31 2015 *)
    b[n_, i_] := b[n, i] = If[n==0 || i==1, Max[1, n], Max[Table[b[n-i*j, i-1]*Max[1, j], {j, 0, n/i}]]]; a[n_] := b[n, n]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Sep 01 2016, after Alois P. Heinz *)

A353698 Number of integer partitions of n whose product equals their length.

Original entry on oeis.org

0, 1, 0, 1, 0, 1, 1, 1, 0, 2, 0, 2, 1, 2, 0, 2, 1, 2, 1, 1, 1, 4, 1, 2, 1, 2, 1, 3, 0, 3, 2, 2, 1, 5, 0, 1, 2, 5, 1, 4, 0, 3, 3, 2, 1, 4, 2, 3, 2, 2, 0, 5, 1, 4, 2, 2, 3, 6, 1, 2, 2, 5, 1, 4, 0, 4, 3, 3, 1, 6, 2, 3, 4, 4, 2, 4, 1, 4, 2, 3, 1, 8, 2, 4, 2, 4, 2, 5, 2, 4, 2
Offset: 0

Views

Author

Gus Wiseman, May 19 2022

Keywords

Examples

			The a(n) partitions for selected n (A..H = 10..17):
n=9:    n=21:             n=27:                 n=33:
---------------------------------------------------------------------------
51111   B1111111111       E1111111111111        H1111111111111111
321111  72111111111111    921111111111111111    B211111111111111111111
        531111111111111   54111111111111111111  831111111111111111111111
        4221111111111111                        5511111111111111111111111
                                                333111111111111111111111111
		

Crossrefs

The LHS (product of parts) is counted by A339095, rank statistic A003963.
The RHS (length) is counted by A008284, rank statistic A001222.
These partitions are ranked by A353699.
A266477 counts partitions by product of multiplicities, rank stat A005361.
A353504 counts partitions w/ product less than product of multiplicities.
A353505 counts partitions w/ product greater than product of multiplicities.
A353506 counts partitions w/ prod equal to prod of mults, ranked by A353503.

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n],Times@@#==Length[#]&]],{n,0,30}]
  • PARI
    a(r,m=r,p=1,k=0) = {(p==k+r) + sum(m=2, min(m, (k+r)\p),  self()(r-m, min(m,r-m), p*m, k+1))} \\ Andrew Howroyd, Jan 02 2023

Extensions

Terms a(61) and beyond from Andrew Howroyd, Jan 02 2023

A266871 Number of partitions of n that maximize the product of multiplicities of parts.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 2, 1, 1, 1, 2, 1, 1, 3, 1, 1, 1, 5, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 3, 1, 1, 1, 5, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 4, 1, 1, 1, 2, 1
Offset: 0

Views

Author

Emeric Deutsch and Alois P. Heinz, Jan 04 2016

Keywords

Examples

			a(8) = 2: [1,1,1,1,1,1,1,1], [1,1,1,1,2,2] (product of multiplicities = 8).
a(9) = 1: [1,1,1,1,1,2,2] (product = 10).
a(10) = 2: [1,1,1,1,1,1,2,2], [1,1,1,1,2,2,2] (product = 12).
a(11) = 1: [1,1,1,1,1,2,2,2] (product = 15).
a(23) = 3: [1,1,1,1,1,1,1,1,1,2,2,2,2,3,3], [1,1,1,1,1,1,1,1,2,2,2,3,3,3], [1,1,1,1,1,1,2,2,2,2,3,3,3] (product = 72).
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; local r,l,j;
          if n=0 or i=1 then [max(1, n),1]
        else r:= b(n, i-1);
             for j to iquo(n, i) do
               l:= (w-> [w[1]*j, w[2]])(b(n-i*j, i-1));
               r:= `if`(l[1]>r[1], l,
                   `if`(l[1]=r[1], [0, l[2]], 0)+r)
             od; r
          fi
        end:
    a:= n-> b(n$2)[2]:
    seq(a(n), n=1..120);
  • Mathematica
    b[n_, i_] := b[n, i] = Module[{r, l, j}, If[n == 0 || i == 1, {Max[1, n], 1}, r = b[n, i - 1]; For[j = 1, j <= Quotient[n, i], j++, l = Function[w, {w[[1]]*j, w[[2]]}][b[n - i*j, i - 1]]; r = If[l[[1]] > r[[1]], l, If[l[[1]] == r[[1]], {0, l[[2]]}, 0] + r]]; r]]; a[n_] := b[n, n][[2]]; Table[a[n], {n, 0, 120}] (* Jean-François Alcover, Dec 21 2016, translated from Maple *)

Formula

a(n) = A266477(n,A266480(n)).

A266325 Smallest integer m such that there is a partition of m with product of multiplicities of parts equal to n.

Original entry on oeis.org

0, 2, 3, 4, 5, 6, 7, 8, 9, 9, 11, 10, 13, 11, 11, 12, 17, 12, 19, 13, 13, 15, 23, 14, 15, 17, 15, 15, 29, 16, 31, 16, 17, 21, 17, 17, 37, 23, 19, 18, 41, 19, 43, 19, 19, 27, 47, 20, 21, 20, 23, 21, 53, 21, 21, 21, 25, 33, 59, 22, 61, 35, 22, 22, 23, 23, 67, 25
Offset: 1

Views

Author

Emeric Deutsch and Alois P. Heinz, Jan 04 2016

Keywords

Crossrefs

Cf. A266477.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(n=0, `if`(p=1, 1, 0),
          `if`(i<1, 0, b(n, i-1, p)+add(`if`(irem(p, j)=0,
           b(n-i*j, i-1, p/j), 0), j=1..n/i)))
        end:
    a:= proc(n) option remember; local m;
          if isprime(n) then return n fi;
          for m from 0 do if b(m$2, n)>0 then return m fi od
        end:
    seq(a(n), n=1..100);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[n == 0, If[p == 1, 1, 0], If[i < 1, 0, b[n, i - 1, p] + Sum[If[Mod[p, j] == 0, b[n - i*j, i - 1, p/j], 0], {j, 1, n/i}]]]; a[n_] := a[n] = Module[{m}, If[PrimeQ[n], Return[n]]; For[m = 0, True, m++, If[b[m, m, n] > 0, Return[m]]]]; Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Dec 21 2016, translated from Maple *)

Formula

a(n) = min { m >= 0 : A266477(m,n) > 0 }.
p in primes => a(p) = p.

A266687 Number of partitions of n with product of multiplicities of parts equal to 4.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 2, 1, 3, 4, 6, 6, 11, 13, 17, 24, 29, 36, 48, 59, 72, 96, 111, 138, 170, 207, 245, 305, 362, 432, 517, 616, 723, 868, 1013, 1194, 1412, 1644, 1915, 2245, 2605, 3019, 3511, 4051, 4677, 5410, 6209, 7125, 8199, 9372, 10718, 12257, 13975, 15902
Offset: 0

Views

Author

Emeric Deutsch and Alois P. Heinz, Jan 02 2016

Keywords

Examples

			a(6) = 2: [1,1,1,1,2], [1,1,2,2].
a(7) = 1: [1,1,1,1,3].
a(8) = 3: [2,2,2,2], [1,1,3,3], [1,1,1,1,4].
a(9) = 4: [1,2,2,2,2], [1,1,1,1,2,3], [1,1,2,2,3], [1,1,1,1,5].
a(10) = 6: [1,1,2,3,3], [2,2,3,3], [1,1,1,1,2,4], [1,1,2,2,4], [1,1,4,4], [1,1,1,1,6].
		

Crossrefs

Column k=4 of A266477.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(n=0, `if`(p=1, 1, 0),
          `if`(i<1, 0, b(n, i-1, p)+add(`if`(irem(p, j)=0,
           b(n-i*j, i-1, p/j), 0), j=1..n/i)))
        end:
    a:= n-> b(n$2, 4):
    seq(a(n), n=0..70);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[n == 0, If[p == 1, 1, 0], If[i < 1, 0, b[n, i - 1, p] + Sum[If[Mod[p, j] == 0, b[n - i*j, i - 1, p/j], 0], {j, 1, n/i}]]]; a[n_] := b[n, n, 4]; Table[a[n], {n, 0, 70}] (* Jean-François Alcover, Dec 22 2016, after Alois P. Heinz *)

Formula

a(n) ~ c * exp(Pi*sqrt(n/3)) * n^(1/4), where c = 0.0108735520090052... - Vaclav Kotesovec, May 24 2018

A266688 Number of partitions of n with product of multiplicities of parts equal to 5.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 3, 3, 3, 4, 7, 8, 10, 12, 15, 18, 24, 28, 35, 42, 48, 60, 72, 84, 102, 120, 140, 166, 194, 226, 264, 311, 358, 416, 482, 554, 641, 738, 844, 970, 1112, 1271, 1450, 1654, 1878, 2138, 2429, 2748, 3116, 3524, 3976, 4493, 5065, 5696
Offset: 0

Views

Author

Emeric Deutsch and Alois P. Heinz, Jan 02 2016

Keywords

Comments

Also the number of partitions of n such that there is exactly one part which occurs 5 times, while all other parts occur only once.

Examples

			a(9) = 1: [1,1,1,1,1,4].
a(10) = 3: [2,2,2,2,2], [1,1,1,1,1,2,3], [1,1,1,1,1,5].
		

Crossrefs

Column k=5 of A266477.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(i*(p+(i-1)/2)0, 0, (h->
           b(h, min(h, i-1), p/j))(n-i*j)), j=1..min(p, n/i))))
        end:
    a:= n-> b(n$2, 5):
    seq(a(n), n=0..65);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[i*(p + (i - 1)/2) < n, 0, If[n == 0, If[p == 1, 1, 0], b[n, i - 1, p] + Sum[If[Mod[p, j] > 0, 0, Function[h, b[h, Min[h, i - 1], p/j]][n - i*j]], {j, 1, Min[p, n/i]}]]];
    a[n_] := b[n, n, 5];
    Table[a[n], {n, 0, 65}] (* Jean-François Alcover, May 01 2018, translated from Maple *)

Formula

G.f.: Sum_{k>=1} x^(5*k)/(1+x^k) * Product_{j>=1} (1+x^j).
a(n) ~ c * exp(Pi*sqrt(n/3)) / n^(1/4), where c = (12*log(2) - 7) / (8*3^(3/4)*Pi) = 0.023001573808... - Vaclav Kotesovec, May 24 2018

A266689 Number of partitions of n with product of multiplicities of parts equal to 6.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 2, 7, 6, 12, 11, 16, 22, 32, 35, 51, 61, 70, 95, 118, 144, 177, 222, 257, 313, 382, 459, 547, 664, 770, 933, 1092, 1275, 1513, 1786, 2070, 2431, 2838, 3287, 3830, 4435, 5094, 5918, 6825, 7821, 9010, 10340, 11820, 13525, 15474
Offset: 0

Views

Author

Emeric Deutsch and Alois P. Heinz, Jan 02 2016

Keywords

Examples

			a(7) = 1: [1,1,1,2,2].
a(8) = 2: [1,1,1,1,1,1,2], [1,1,2,2,2].
a(11) = 7: [1,1,1,1,1,1,2,3], [1,1,2,2,2,3], [1,1,1,2,3,3], [1,1,3,3,3], [1,1,1,2,2,4], [1,1,1,4,4], [1,1,1,1,1,1,5].
		

Crossrefs

Column k=6 of A266477.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(i*(p+(i-1)/2)0, 0, (h->
           b(h, min(h, i-1), p/j))(n-i*j)), j=1..min(p, n/i))))
        end:
    a:= n-> b(n$2, 6):
    seq(a(n), n=0..65);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[i*(p + (i - 1)/2) < n, 0, If[n == 0, If[p == 1, 1, 0], b[n, i - 1, p] + Sum[If[Mod[p, j] > 0, 0, Function[h, b[h, Min[h, i - 1], p/j]][n - i*j]], {j, 1, Min[p, n/i]}]]];
    a[n_] := b[n, n, 6];
    Table[a[n], {n, 0, 65}] (* Jean-François Alcover, May 01 2018, translated from Maple *)

Formula

a(n) ~ c * exp(Pi*sqrt(n/3)) * n^(1/4), where c = 0.01368862060... - Vaclav Kotesovec, May 24 2018

A266690 Number of partitions of n with product of multiplicities of parts equal to 7.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 2, 2, 4, 4, 5, 6, 9, 10, 12, 16, 20, 23, 28, 33, 40, 49, 59, 69, 81, 96, 112, 133, 155, 181, 212, 246, 284, 331, 380, 438, 506, 580, 666, 765, 872, 996, 1136, 1294, 1468, 1669, 1894, 2142, 2426, 2740, 3092, 3488, 3926, 4416
Offset: 0

Views

Author

Emeric Deutsch and Alois P. Heinz, Jan 02 2016

Keywords

Comments

Also the number of partitions of n such that there is exactly one part which occurs 7 times, while all other parts occur only once.

Examples

			a(11) = 1: [1,1,1,1,1,1,1,4].
a(12) = 2: [1,1,1,1,1,1,1,2,3], [1,1,1,1,1,1,1,5].
		

Crossrefs

Column k=7 of A266477.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(i*(p+(i-1)/2)0, 0, (h->
           b(h, min(h, i-1), p/j))(n-i*j)), j=1..min(p, n/i))))
        end:
    a:= n-> b(n$2, 7):
    seq(a(n), n=0..65);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[i*(p + (i - 1)/2) < n, 0, If[n == 0, If[p == 1, 1, 0], b[n, i - 1, p] + Sum[If[Mod[p, j] > 0, 0, Function[h, b[h, Min[h, i - 1], p/j]][n - i*j]], {j, 1, Min[p, n/i]}]]];
    a[n_] := b[n, n, 7];
    Table[a[n], {n, 0, 65}] (* Jean-François Alcover, May 01 2018, translated from Maple *)

Formula

G.f.: Sum_{k>=1} x^(7*k)/(1+x^k) * Product_{j>=1} (1+x^j).
a(n) ~ c * exp(Pi*sqrt(n/3)) / n^(1/4), where c = (60*log(2)-37) / (40*3^(3/4)*Pi) = 0.016019584320... - Vaclav Kotesovec, May 24 2018

A266691 Number of partitions of n with product of multiplicities of parts equal to 8.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 3, 2, 5, 4, 10, 9, 17, 20, 25, 31, 47, 53, 71, 89, 109, 138, 171, 205, 257, 317, 375, 461, 557, 664, 792, 962, 1124, 1352, 1596, 1878, 2215, 2621, 3042, 3584, 4180, 4862, 5658, 6593, 7598, 8826, 10190, 11730, 13516, 15562, 17811
Offset: 0

Views

Author

Emeric Deutsch and Alois P. Heinz, Jan 02 2016

Keywords

Examples

			a(8) = 2: [1,1,1,1,1,1,1,1], [1,1,1,1,2,2].
a(10) = 3: [1,1,1,1,1,1,1,1,2], [1,1,2,2,2,2], [1,1,1,1,3,3].
a(12) = 5: [1,1,1,1,2,3,3], [1,1,2,2,3,3], [1,1,1,1,1,1,1,1,4], [1,1,1,1,2,2,4], [1,1,1,1,4,4].
		

Crossrefs

Column k=8 of A266477.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(i*(p+(i-1)/2)0, 0, (h->
           b(h, min(h, i-1), p/j))(n-i*j)), j=1..min(p, n/i))))
        end:
    a:= b(n$2, 8):
    seq(a(n), n=0..65);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[i*(p + (i - 1)/2) < n, 0, If[n == 0, If[p == 1, 1, 0], b[n, i - 1, p] + Sum[If[Mod[p, j] > 0, 0, Function[h, b[h, Min[h, i - 1], p/j]][n - i*j]], {j, 1, Min[p, n/i]}]]];
    a[n_] := b[n, n, 8];
    Table[a[n], {n, 0, 65}] (* Jean-François Alcover, May 01 2018, translated from Maple *)

Formula

a(n) ~ c * exp(Pi*sqrt(n/3)) * n^(3/4), where c = 0.0012263686774... - Vaclav Kotesovec, May 24 2018
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