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 1-10 of 10 results.

A300061 Heinz numbers of integer partitions of even numbers.

Original entry on oeis.org

1, 3, 4, 7, 9, 10, 12, 13, 16, 19, 21, 22, 25, 27, 28, 29, 30, 34, 36, 37, 39, 40, 43, 46, 48, 49, 52, 53, 55, 57, 61, 62, 63, 64, 66, 70, 71, 75, 76, 79, 81, 82, 84, 85, 87, 88, 89, 90, 91, 94, 100, 101, 102, 107, 108, 111, 112, 113, 115, 116, 117, 118, 120
Offset: 1

Views

Author

Gus Wiseman, Feb 23 2018

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			75 is the Heinz number of (3,3,2), which has even weight, so 75 belongs to the sequence.
Sequence of even-weight partitions begins: () (2) (1,1) (4) (2,2) (3,1) (2,1,1) (6) (1,1,1,1) (8) (4,2) (5,1) (3,3) (2,2,2) (4,1,1).
		

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; local k; for k from 1+
         `if`(n=1, 0, a(n-1)) while add(numtheory[pi]
          (i[1])*i[2], i=ifactors(k)[2])::odd do od; k
        end:
    seq(a(n), n=1..100);  # Alois P. Heinz, May 22 2018
  • Mathematica
    Select[Range[200],EvenQ[Total[Cases[FactorInteger[#],{p_,k_}:>k*PrimePi[p]]]]&]

A300063 Heinz numbers of integer partitions of odd numbers.

Original entry on oeis.org

2, 5, 6, 8, 11, 14, 15, 17, 18, 20, 23, 24, 26, 31, 32, 33, 35, 38, 41, 42, 44, 45, 47, 50, 51, 54, 56, 58, 59, 60, 65, 67, 68, 69, 72, 73, 74, 77, 78, 80, 83, 86, 92, 93, 95, 96, 97, 98, 99, 103, 104, 105, 106, 109, 110, 114, 119, 122, 123, 124, 125, 126, 127
Offset: 1

Views

Author

Gus Wiseman, Feb 23 2018

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			15 is the Heinz number of (3,2), which has odd weight, so 15 belongs to the sequence.
Sequence of odd-weight partitions begins: (1) (3) (2,1) (1,1,1) (5) (4,1) (3,2) (7) (2,2,1) (3,1,1) (9) (2,1,1,1) (6,1).
		

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; local k; for k from 1+
         `if`(n=1, 0, a(n-1)) while add(numtheory[pi]
          (i[1])*i[2], i=ifactors(k)[2])::even do od; k
        end:
    seq(a(n), n=1..100);  # Alois P. Heinz, May 22 2018
  • Mathematica
    Select[Range[200],OddQ[Total[Cases[FactorInteger[#],{p_,k_}:>k*PrimePi[p]]]]&]

A300060 Number of domino tilings of the diagram of the integer partition with Heinz number n.

Original entry on oeis.org

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

Views

Author

Gus Wiseman, Feb 23 2018

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Crossrefs

Programs

  • Maple
    h:= proc(l, f) option remember; local k; if min(l[])>0 then
         `if`(nops(f)=0, 1, h(map(x-> x-1, l[1..f[1]]), subsop(1=[][], f)))
        else for k from nops(l) while l[k]>0 by -1 do od;
            `if`(nops(f)>0 and f[1]>=k, h(subsop(k=2, l), f), 0)+
            `if`(k>1 and l[k-1]=0, h(subsop(k=1, k-1=1, l), f), 0)
          fi
        end:
    g:= l-> `if`(add(`if`(l[i]::odd, (-1)^i, 0), i=1..nops(l))=0,
            `if`(l=[], 1, h([0$l[1]], subsop(1=[][], l))), 0):
    a:= n-> g(sort(map(i-> numtheory[pi](i[1])$i[2], ifactors(n)[2]), `>`)):
    seq(a(n), n=1..120);  # Alois P. Heinz, May 22 2018
  • Mathematica
    h[l_, f_] := h[l, f] = Module[{k}, If[Min[l] > 0, If[Length[f] == 0, 1, h[Map[Function[x, x-1], l[[Range @ f[[1]]]]], ReplacePart[f, 1 -> Nothing]]], For[k = Length[l], l[[k]] > 0, k-- ]; If[Length[f] > 0 && f[[1]] >= k, h[ReplacePart[l, k -> 2], f], 0] + If[k > 1 && l[[k-1]] == 0, h[ReplacePart[l, {k -> 1, k - 1 -> 1}], f], 0]]];
    g[l_] := If[Sum[If[OddQ @ l[[i]], (-1)^i, 0], {i, 1, Length[l]}] == 0, If[l == {}, 1, h[Table[0, l[[1]]], ReplacePart[l, 1 -> Nothing]]], 0];
    a[n_] := g[Reverse @ Sort[ Flatten[ Map[ Function[i, Table[PrimePi[i[[1]]], i[[2]]]], FactorInteger[n]]]]];
    Array[a, 120] (* Jean-François Alcover, May 28 2018, after Alois P. Heinz *)

A300789 Heinz numbers of integer partitions whose Young diagram can be tiled by dominos.

Original entry on oeis.org

1, 3, 4, 7, 9, 10, 12, 13, 16, 19, 21, 22, 25, 27, 28, 29, 34, 36, 37, 39, 40, 43, 46, 48, 49, 52, 53, 55, 57, 61, 62, 63, 64, 70, 71, 75, 76, 79, 81, 82, 84, 85, 87, 88, 89, 90, 91, 94, 100, 101, 107, 108, 111, 112, 113, 115, 116, 117, 118, 121, 129, 130, 131
Offset: 1

Views

Author

Gus Wiseman, Mar 12 2018

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
This sequence is conjectured to be the Heinz numbers of integer partitions in which the odd parts appear as many times in even as in odd positions.

Examples

			Sequence of integer partitions whose Young diagram can be tiled by dominos begins: (), (2), (11), (4), (22), (31), (211), (6), (1111), (8), (42), (51), (33), (222), (411).
		

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; local k; for k from 1+
          `if`(n=1, 0, a(n-1)) while (l-> add(`if`(l[i]::odd,
           (-1)^i, 0), i=1..nops(l))<>0)(sort(map(i->
           numtheory[pi](i[1])$i[2], ifactors(k)[2]))) do od; k
        end:
    seq(a(n), n=1..100);  # Alois P. Heinz, May 22 2018
  • Mathematica
    primeMS[n_]:=If[n===1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
    Select[Range[100],Total[(-1)^Flatten[Position[primeMS[#],_?OddQ]]]===0&] (* Conjectured *)

A304710 Number of partitions of 2n whose Ferrers-Young diagram cannot be tiled with dominoes.

Original entry on oeis.org

0, 0, 0, 1, 2, 6, 12, 25, 46, 85, 146, 250, 410, 666, 1053, 1648, 2527, 3840, 5747, 8525, 12496, 18172, 26165, 37408, 53038, 74714, 104502, 145315, 200808, 276030, 377339, 513342, 694925, 936590, 1256670, 1679310, 2234994, 2963430, 3914701, 5153434, 6760937
Offset: 0

Views

Author

Alois P. Heinz, May 17 2018

Keywords

Comments

Also the number of partitions of 2n where the number of odd parts in even positions differs from the number of odd parts in odd positions.

Examples

			a(3) = 1: the Ferrers-Young diagram of 321 cannot be tiled with dominoes because the numbers of white and black squares (when colored like a chessboard) are different but each domino covers exactly one white and one black square:
   ._____.
   |_|X|_|
   |X|_|
   |_|
.
a(4) = 2: 32111, 521.
a(5) = 6: 3211111, 32221, 4321, 52111, 541, 721.
a(6) = 12: 321111111, 3222111, 33321, 432111, 5211111, 52221, 54111, 543, 6321, 72111, 741, 921.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i, p, c) option remember; `if`(n=0, `if`(c=0, 0, 1),
          `if`(i<1, 0, b(n, i-1, p, c)+b(n-i, min(n-i, i), -p, c+
          `if`(i::odd, p, 0))))
        end:
    a:= n-> b(2*n$2, 1, 0):
    seq(a(n), n=0..50);
    # second Maple program:
    a:= n-> (p-> p(2*n)-add(p(j)*p(n-j), j=0..n))(combinat[numbpart]):
    seq(a(n), n=0..50);
    # third Maple program:
    b:= proc(n, k) option remember; `if`(n=0, 1, add(
          numtheory[sigma](j)*b(n-j, k), j=1..n)*k/n)
        end:
    a:= n-> b(2*n, 1)-b(n, 2):
    seq(a(n), n=0..50);
  • Mathematica
    b[n_, i_, p_, c_] := b[n, i, p, c] = If[n == 0, If[c == 0, 0, 1], If[i < 1, 0, b[n, i - 1, p, c] + b[n - i, Min[n - i, i], -p, c + If[OddQ[i], p, 0]]]];
    a[n_] := b[2n, 2n, 1, 0];
    Table[a[n], {n, 0, 50}]
    (* second program: *)
    a[n_] := PartitionsP[2n] - Sum[PartitionsP[j]* PartitionsP[n - j], {j, 0, n}];
    Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Feb 13 2023, after Alois P. Heinz *)

Formula

a(n) = A058696(n) - A000712(n) = A000041(2*n) - A000712(n).
a(n) = A144064(2*n,1) - A144064(n,2).
a(n) ~ exp(2*Pi*sqrt(n/3)) / (8*sqrt(3)*n) * (1 - 2/(3^(1/4)*n^(1/4)) - (sqrt(3)/(2*Pi) + Pi/(48*sqrt(3))) / sqrt(n) + (Pi/(6*3^(3/4)) + 15*3^(1/4)/(8*Pi)) / n^(3/4)). - Vaclav Kotesovec, May 25 2018

A304789 Number T(n,k) of partitions of 2n whose Ferrers-Young diagram allows exactly k different domino tilings; triangle T(n,k), n>=0, 0<=k<=A304790(n), read by rows.

Original entry on oeis.org

0, 1, 0, 2, 0, 4, 1, 1, 6, 2, 2, 2, 10, 3, 4, 1, 2, 6, 14, 4, 6, 4, 4, 0, 2, 2, 12, 22, 5, 8, 7, 6, 2, 4, 4, 0, 0, 4, 1, 2, 25, 30, 6, 10, 12, 10, 4, 6, 6, 0, 2, 8, 2, 4, 0, 2, 0, 0, 4, 2, 0, 2, 46, 44, 7, 12, 17, 14, 8, 8, 8, 0, 4, 12, 5, 6, 0, 8, 2, 0, 8, 4, 0, 4, 0, 0, 0, 2, 2, 0, 0, 4, 1, 2, 0, 0, 2, 0, 1
Offset: 0

Views

Author

Alois P. Heinz, May 18 2018

Keywords

Examples

			T(2,2) = 1: 22.
T(3,0) = 1: 321.
T(3,1) = 6: 111111, 21111, 3111, 411, 51, 6.
T(3,2) = 2: 2211, 42.
T(3,3) = 2: 222, 33.
T(8,36) = 1: 4444.
Triangle T(n,k) begins:
   0,  1;
   0,  2;
   0,  4, 1;
   1,  6, 2,  2;
   2, 10, 3,  4,  1,  2;
   6, 14, 4,  6,  4,  4, 0, 2, 2;
  12, 22, 5,  8,  7,  6, 2, 4, 4, 0, 0, 4, 1, 2;
  25, 30, 6, 10, 12, 10, 4, 6, 6, 0, 2, 8, 2, 4, 0, 2, 0, 0, 4, 2, 0, 2;
		

Crossrefs

Columns k=0-1 give: A304710, A139582(n) = 2*A000041(n) for n>0.
Row sums give A058696(n) or A000041(2n).

Programs

  • Maple
    h:= proc(l, f) option remember; local k; if min(l[])>0 then
         `if`(nops(f)=0, 1, h(map(u-> u-1, l[1..f[1]]), subsop(1=[][], f)))
        else for k from nops(l) while l[k]>0 by -1 do od;
            `if`(nops(f)>0 and f[1]>=k, h(subsop(k=2, l), f), 0)+
            `if`(k>1 and l[k-1]=0, h(subsop(k=1, k-1=1, l), f), 0)
          fi
        end:
    g:= l-> x^`if`(add(`if`(l[i]::odd, (-1)^i, 0), i=1..nops(l))=0,
              `if`(l=[], 1, h([0$l[1]], subsop(1=[][], l))), 0):
    b:= (n, i, l)-> `if`(n=0 or i=1, g([l[], 1$n]), b(n, i-1, l)
                      +b(n-i, min(n-i, i), [l[], i])):
    T:= n-> (p-> seq(coeff(p, x, i), i=0..degree(p)))(b(2*n$2, [])):
    seq(T(n), n=0..11);

Formula

Sum_{k>0} k * T(n,k) = A304662(n).
T(n,A304790(n)) = 1 for n in { A001105 }.
Sum_{k>=0} T(n,k) = A058696(n) = A000041(2n).
Sum_{k>=1} T(n,k) = A000712(n).
Sum_{k>=2} T(n,k) = A048574(n) = A052837(n).

A296625 a(n) is the total multiplicity of all products of Schur functions s(lambda)*s(lambda) with lambda a partition of n.

Original entry on oeis.org

1, 2, 6, 16, 42, 106, 268, 660, 1618, 3922, 9438, 22540, 53528, 126358
Offset: 0

Views

Author

Wouter Meeussen, Dec 17 2017

Keywords

Comments

Diagonal of the matrix formed by products of all pairs of partitions.
Conjecture: a(n) is the number of domino tilings of diagrams of integer partitions of 2n. - Gus Wiseman, Feb 25 2018
The above conjecture is not true, see A304662. - Alois P. Heinz, May 22 2018

Examples

			for n=2,
s(2)*s(2) = s(4) + s(3,1) + s(2,2) and
s(1,1) * s(1,1) = s(2,2) + s(2,1,1) + s(1,1,1,1)
for 6 terms in total.
		

Crossrefs

Programs

  • Mathematica
    Table[Sum[Length[LRRule[\[Lambda], \[Lambda]]], {\[Lambda], Partitions[n]}], {n, 0, 7}];
    (* Uses the Mathematica toolbox for Symmetric Functions from A296624. *)

Formula

a(n) = A304662(n) for n < 7. - Alois P. Heinz, May 22 2018

Extensions

a(13)-a(14) from Wouter Meeussen, Nov 22 2018

A304718 Number T(n,k) of domino tilings of Ferrers-Young diagrams of partitions of 2n using exactly k horizontally oriented dominoes; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 3, 5, 5, 3, 5, 9, 14, 9, 5, 7, 18, 28, 28, 18, 7, 11, 29, 63, 62, 63, 29, 11, 15, 51, 109, 150, 150, 109, 51, 15, 22, 79, 206, 293, 380, 293, 206, 79, 22, 30, 126, 342, 590, 787, 787, 590, 342, 126, 30, 42, 189, 584, 1061, 1675, 1760, 1675, 1061, 584, 189, 42
Offset: 0

Views

Author

Alois P. Heinz, May 17 2018

Keywords

Examples

			:   T(2,0) = 2   :   T(2,1) = 2       :   T(2,2) = 2         :
:   ._.  ._._.   :   .___.  ._.___.   :   .___.  .___.___.   :
:   | |  | | |   :   |___|  | |___|   :   |___|  |___|___|   :
:   |_|  |_|_|   :   | |    |_|       :   |___|              :
:   | |          :   |_|              :                      :
:   |_|          :                    :                      :
:                :                    :                      :
Triangle T(n,k) begins:
   1;
   1,   1;
   2,   2,   2;
   3,   5,   5,    3;
   5,   9,  14,    9,    5;
   7,  18,  28,   28,   18,    7;
  11,  29,  63,   62,   63,   29,   11;
  15,  51, 109,  150,  150,  109,   51,   15;
  22,  79, 206,  293,  380,  293,  206,   79,  22;
  30, 126, 342,  590,  787,  787,  590,  342, 126,  30;
  42, 189, 584, 1061, 1675, 1760, 1675, 1061, 584, 189, 42;
  ...
		

Crossrefs

Row sums give A304662.
Main diagonal and column k=0 give A000041.
T(n,floor(n/2)) gives A304719.

Programs

  • Maple
    h:= proc(l, f) option remember; local k; if min(l[])>0 then
         `if`(nops(f)=0, 1, h(map(u-> u-1, l[1..f[1]]), subsop(1=[][], f)))
        else for k from nops(l) while l[k]>0 by -1 do od; expand(
            `if`(nops(f)>0 and f[1]>=k, x*h(subsop(k=2, l), f), 0)+
            `if`(k>1 and l[k-1]=0, h(subsop(k=1, k-1=1, l), f), 0))
          fi
        end:
    g:= l-> `if`(add(`if`(l[i]::odd, (-1)^i, 0), i=1..nops(l))=0,
            `if`(l=[], 1, h([0$l[1]], subsop(1=[][], l))), 0):
    b:= (n, i, l)-> `if`(n=0 or i=1, g([l[], 1$n]), b(n, i-1, l)
                      +b(n-i, min(n-i, i), [l[], i])):
    T:= n-> (p-> seq(coeff(p, x, i), i=0..degree(p)))(b(2*n$2, [])):
    seq(T(n), n=0..12);
  • Mathematica
    h[l_, f_] := h[l, f] = Module[{k}, If[Min[l] > 0, If[Length[f] == 0, 1, h[l[[1 ;; f[[1]] ]] - 1, ReplacePart[f, 1 -> Nothing]]], For[k = Length[l], l[[k]] > 0, k--]; If[Length[f] > 0 && f[[1]] >= k, x*h[ReplacePart[l, k -> 2], f], 0] + If[k > 1 && l[[k - 1]] == 0, h[ReplacePart[l, {k -> 1, k - 1 -> 1}], f], 0]]];
    g[l_] := If[Sum[If[OddQ[l[[i]]], (-1)^i, 0], {i, 1, Length[l]}] == 0, If[l == {}, 1, h[Table[0, {l[[1]]}], ReplacePart[l, 1 -> Nothing]]], 0];
    b[n_, i_, l_] := If[n == 0 || i == 1, g[Join[l, Table[1, {n}]]], b[n, i - 1, l] + b[n - i, Min[n - i, i], Append[l, i]]];
    T[n_] := CoefficientList[b[2n, 2n, {}], x];
    Table[T[n], {n, 0, 12}] // Flatten (* Jean-François Alcover, Aug 29 2021, after Alois P. Heinz *)

Formula

T(n,k) = T(n,n-k).

A304677 Total number of tilings of Ferrers-Young diagrams using dominoes and monominoes summed over all partitions of n.

Original entry on oeis.org

1, 1, 4, 9, 27, 60, 170, 377, 996, 2288, 5715, 13002, 32321, 72864, 175137, 400039, 943454, 2133159, 4993737, 11236889, 25995341, 58480330, 133650880, 299347432, 681346296, 1519116099, 3427954877, 7631479391, 17122129103, 37958987956, 84819325972, 187405201004
Offset: 0

Views

Author

Alois P. Heinz, May 16 2018

Keywords

Crossrefs

Programs

  • Maple
    h:= proc(l, f) option remember; local k; if min(l[])>0 then
         `if`(nops(f)=0, 1, h(map(x-> x-1, l[1..f[1]]), subsop(1=[][], f)))
        else for k from nops(l) while l[k]>0 by -1 do od; h(subsop(k=1, l), f)+
            `if`(nops(f)>0 and f[1]>=k, h(subsop(k=2, l), f), 0)+
            `if`(k>1 and l[k-1]=0, h(subsop(k=1, k-1=1, l), f), 0)
          fi
        end:
    g:= l-> `if`(l=[], 1, h([0$l[1]], subsop(1=[][], l))):
    b:= (n, i, l)-> `if`(n=0 or i=1, g([l[], 1$n]), b(n, i-1, l)
                      +b(n-i, min(n-i, i), [l[], i])):
    a:= n-> b(n$2, []):
    seq(a(n), n=0..23);

A304680 Total number of tilings of Ferrers-Young diagrams using dominoes and at most one monomino summed over all partitions of n.

Original entry on oeis.org

1, 1, 2, 6, 6, 23, 16, 76, 42, 239, 106, 688, 268, 1931, 650, 5266, 1580, 13861, 3750, 35810, 8862, 91065, 20598, 226914, 47776, 559271, 109248, 1360152, 248966, 3270429, 562630, 7785974, 1264780, 18378067, 2823958, 43007532, 6282198, 99892837, 13884820
Offset: 0

Views

Author

Alois P. Heinz, May 16 2018

Keywords

Crossrefs

Bisection (even part) gives A304662.
Cf. A304677.

Programs

  • Maple
    h:= proc(l, f, t) option remember; local k; if min(l[])>0 then
         `if`(nops(f)=0, 1, h(map(x-> x-1, l[1..f[1]]), subsop(1=[][], f), t))
        else for k from nops(l) while l[k]>0 by -1 do od;
            `if`(t, h(subsop(k=1, l), f, false), 0)+
            `if`(nops(f)>0 and f[1]>=k, h(subsop(k=2, l), f, t), 0)+
            `if`(k>1 and l[k-1]=0, h(subsop(k=1, k-1=1, l), f, t), 0)
          fi
        end:
    g:= l-> (t-> `if`(l=[], 1, h([0$l[1]], subsop(1=[][], l),
                   is(t, odd))))(add(i, i=l)):
    b:= (n, i, l)-> `if`(n=0 or i=1, g([l[], 1$n]), b(n, i-1, l)
                      +b(n-i, min(n-i, i), [l[], i])):
    a:= n-> b(n$2, []):
    seq(a(n), n=0..23);
Showing 1-10 of 10 results.