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 1-3 of 3 results.

A276429 Number of partitions of n containing no part i of multiplicity i.

Original entry on oeis.org

1, 0, 2, 2, 3, 5, 8, 9, 16, 19, 29, 36, 53, 65, 92, 115, 154, 195, 257, 318, 419, 516, 663, 821, 1039, 1277, 1606, 1963, 2441, 2978, 3675, 4454, 5469, 6603, 8043, 9688, 11732, 14066, 16963, 20260, 24310, 28953, 34586, 41047, 48857, 57802, 68528, 80862, 95534, 112388, 132391
Offset: 0

Views

Author

Emeric Deutsch, Sep 19 2016

Keywords

Comments

The Heinz numbers of these partitions are given by A325130. - Gus Wiseman, Apr 02 2019

Examples

			a(4) = 3 because we have [1,1,1,1], [1,1,2], and [4]; the partitions [1,3], [2,2] do not qualify.
From _Gus Wiseman_, Apr 02 2019: (Start)
The a(2) = 2 through a(7) = 9 partitions:
  (2)   (3)    (4)     (5)      (6)       (7)
  (11)  (111)  (211)   (32)     (33)      (43)
               (1111)  (311)    (42)      (52)
                       (2111)   (222)     (511)
                       (11111)  (411)     (3211)
                                (3111)    (4111)
                                (21111)   (31111)
                                (111111)  (211111)
                                          (1111111)
(End)
		

Crossrefs

Programs

  • Maple
    g := product(1/(1-x^i)-x^(i^2), i = 1 .. 100): gser := series(g, x = 0, 53): seq(coeff(gser, x, n), n = 0 .. 50);
    # second Maple program:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(`if`(i=j, 0, b(n-i*j, i-1)), j=0..n/i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..60);  # Alois P. Heinz, Sep 19 2016
  • Mathematica
    b[n_, i_] := b[n, i] = Expand[If[n == 0, 1, If[i < 1, 0, Sum[If[i == j, x, 1]*b[n - i*j, i - 1], {j, 0, n/i}]]]]; T[n_] := Function[p, Table[Coefficient[p, x, i], {i, 0, Exponent[p, x]}]][b[n, n]]; Table[T[n][[1]], {n, 0, 60}] (* Jean-François Alcover, Nov 28 2016 after Alois P. Heinz's Maple code for A276427 *)
    Table[Length[Select[IntegerPartitions[n],And@@Table[Count[#,i]!=i,{i,Union[#]}]&]],{n,0,30}] (* Gus Wiseman, Apr 02 2019 *)

Formula

a(n) = A276427(n,0).
G.f.: g(x) = Product_{i>=1} (1/(1-x^i) - x^{i^2}).

A242434 Number of compositions of n in which each part p has multiplicity p.

Original entry on oeis.org

1, 1, 0, 0, 1, 3, 0, 0, 0, 1, 4, 0, 0, 10, 60, 0, 1, 5, 0, 0, 15, 105, 0, 0, 0, 36, 286, 0, 0, 1281, 12768, 0, 0, 0, 56, 504, 1, 7, 2520, 27720, 28, 378, 1260, 0, 0, 7014, 84000, 0, 0, 4621, 83168, 360360, 210, 2346, 2522880, 37837800, 13860, 180180, 120, 1320
Offset: 0

Views

Author

Alois P. Heinz, May 14 2014

Keywords

Comments

a(n) = 0 for n in {A001422}, a(n) > 0 for n in {A003995}.

Examples

			a(0) = 1: the empty composition.
a(1) = 1: [1].
a(4) = 1: [2,2].
a(5) = 3: [1,2,2], [2,1,2], [2,2,1].
a(9) = 1: [3,3,3].
a(10) = 4: [1,3,3,3], [3,1,3,3], [3,3,1,3], [3,3,3,1].
a(13) = 10: [2,2,3,3,3], [2,3,2,3,3], [2,3,3,2,3], [2,3,3,3,2], [3,2,2,3,3], [3,2,3,2,3], [3,2,3,3,2], [3,3,2,2,3], [3,3,2,3,2], [3,3,3,2,2].
		

Crossrefs

Cf. A033461 (the same for partitions), A336269.

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(n=0, p!, `if`(i<1, 0,
           b(n, i-1, p) +`if`(i^2>n, 0, b(n-i^2, i-1, p+i)/i!)))
        end:
    a:= n-> b(n, isqrt(n), 0):
    seq(a(n), n=0..100);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[n==0, p!, If[i<1, 0, b[n, i-1, p] + If[i^2 >n, 0, b[n-i^2, i-1, p+i]/i!]]]; a[n_] := b[n, Floor[Sqrt[n]], 0]; Table[ a[n], {n, 0, 100}] (* Jean-François Alcover, Feb 08 2017, translated from Maple *)

A336273 Number of compositions of n containing at least one part p of multiplicity p.

Original entry on oeis.org

0, 1, 0, 2, 3, 5, 14, 28, 44, 101, 207, 399, 779, 1609, 3122, 6121, 11804, 23631, 46273, 91604, 178096, 352419, 691996, 1371306, 2702206, 5356324, 10604748, 21080216, 41869930, 83383786, 166114046, 331434088, 661685588, 1322042390, 2642367028, 5283397304
Offset: 0

Views

Author

Alois P. Heinz, Jul 15 2020

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(n=0, p!, `if`(i<1, 0,
          add(`if`(i=j, 0, b(n-i*j, i-1, p+j)/j!), j=0..n/i)))
        end:
    a:= n-> ceil(2^(n-1))-b(n$2, 0):
    seq(a(n), n=0..40);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[n == 0, p!, If[i < 1, 0,
         Sum[If[i == j, 0, b[n - i*j, i - 1, p + j]/j!], {j, 0, n/i}]]];
    a[n_] := Ceiling[2^(n - 1)] - b[n, n, 0];
    Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Apr 14 2022, after Alois P. Heinz *)

Formula

a(n) = A011782(n) - A336269(n).
Showing 1-3 of 3 results.