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 1-9 of 9 results.

A240874 Number of partitions p of n into distinct parts such that max(p) < 2*min(p).

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 4, 5, 6, 6, 7, 7, 7, 8, 9, 10, 10, 11, 11, 12, 14, 14, 15, 17, 17, 18, 19, 20, 23, 24, 25, 26, 28, 29, 31, 34, 35, 37, 40, 42, 44, 46, 48, 51, 55, 58, 61, 64, 67, 70, 75, 77, 82, 87, 90, 96, 101, 105, 111
Offset: 0

Views

Author

Clark Kimberling, Apr 15 2014

Keywords

Examples

			a(12) counts these 3 partitions:  {12}, {7,5}, {5,4,3}.

Links

Crossrefs

Cf. A241035, A241036, A241037.

Programs

  • Mathematica
    z = 70; f[n_] := f[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
Table[Count[f[n], p_ /; Max[p] < 2*Min[p]], {n, 0, z}]  (* this sequence *)
Table[Count[f[n], p_ /; Max[p] == 2*Min[p]], {n, 0, z}] (* A241035 *)
Table[Count[f[n], p_ /; Max[p] >= 2*Min[p]], {n, 0, z}] (* A241036 *)
Table[Count[f[n], p_ /; Max[p] > 2*Min[p]], {n, 0, z}]  (* A241037 *)
  • PARI
    p_q(k) = {prod(j=1,k, 1-q^j);}
GB_q(N,M)= {p_q(N+M)/(p_q(M)*p_q(N));}
A_q(N) = {my(q='q+O('q^N), g=sum(i=1, N, sum(j=i, N-(i*(i+1)/2), q^((i/2)*(i+(2*j)-1)) * GB_q(i-1,j-i))));
concat([0],Vec(g))}
A_q(71) \\ John Tyler Rascoe, Mar 16 2024

Formula

G.f.: Sum_{i>0} Sum_{j>=i} q^((i/2)*(i+(2*j)-1)) * q_binomial(i-1,j-i). - John Tyler Rascoe, Mar 16 2024

A241036 Number of partitions p of n into distinct parts such that max(p) >= 2*min(p).

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 3, 3, 4, 6, 8, 9, 12, 15, 19, 23, 28, 33, 42, 49, 58, 70, 82, 97, 115, 134, 156, 182, 212, 245, 285, 328, 376, 434, 497, 568, 651, 742, 845, 962, 1090, 1236, 1401, 1584, 1788, 2019, 2273, 2556, 2875, 3227, 3618, 4055, 4538, 5074, 5670, 6327
Offset: 0

Views

Author

Clark Kimberling, Apr 15 2014

Keywords

Examples

			a(11) counts these 9 partitions:  {10,1}, {9,2}, {8,3}, {8,2,1}, {7,3,1}, {6,4,1}, {6,3,2}, {5,4,2}, {5,3,2,1}.

Crossrefs

Cf. A240874, A241035, A241037.

Programs

  • Mathematica
    z = 70; f[n_] := f[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
Table[Count[f[n], p_ /; Max[p] < 2*Min[p]], {n, 0, z}]  (* A240874 *)
Table[Count[f[n], p_ /; Max[p] == 2*Min[p]], {n, 0, z}] (* A241035 *)
Table[Count[f[n], p_ /; Max[p] >= 2*Min[p]], {n, 0, z}] (* A241036 *)
Table[Count[f[n], p_ /; Max[p] > 2*Min[p]], {n, 0, z}]  (* A241037 *)

A241037 Number of partitions p of n into distinct parts such that max(p) > 2*min(p).

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 2, 3, 4, 4, 8, 9, 11, 14, 18, 22, 28, 32, 39, 48, 58, 68, 81, 95, 112, 132, 155, 180, 210, 242, 280, 326, 374, 430, 494, 565, 646, 737, 840, 956, 1087, 1232, 1394, 1578, 1781, 2010, 2266, 2550, 2866, 3219, 3610, 4045, 4528, 5062, 5656, 6316
Offset: 0

Views

Author

Clark Kimberling, Apr 15 2014

Keywords

Examples

			a(9) counts these 4 partitions:  {8,1}, {7,2}, {6,2,1}, {5,3,1}.

Crossrefs

Cf. A240874, A241035, A241036.

Programs

  • Mathematica
    z = 70; f[n_] := f[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
Table[Count[f[n], p_ /; Max[p] < 2*Min[p]], {n, 0, z}]  (* A240874 *)
Table[Count[f[n], p_ /; Max[p] == 2*Min[p]], {n, 0, z}] (* A241035 *)
Table[Count[f[n], p_ /; Max[p] >= 2*Min[p]], {n, 0, z}] (* A241036 *)
Table[Count[f[n], p_ /; Max[p] > 2*Min[p]], {n, 0, z}]  (* A241037 *)

A241063 Number of partitions p of n into distinct parts such that max(p) = 3*min(p).

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 2, 1, 0, 1, 3, 2, 1, 1, 3, 2, 2, 3, 4, 3, 3, 5, 4, 5, 5, 7, 7, 7, 7, 7, 9, 10, 10, 11, 13, 14, 14, 14, 15, 17, 19, 22, 24, 23, 24, 28, 28, 31, 32, 36, 39, 42, 43, 46, 49, 53, 56, 59, 65, 68, 73, 77, 81, 87, 92
Offset: 0

Views

Author

Clark Kimberling, Apr 18 2014

Keywords

Examples

			a(12) counts these 2 partitions:  93, 642.

Crossrefs

Cf. A241035, A241069, A241272, A241273.

Programs

  • Mathematica
    z = 40; f[n_] := f[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
    Table[Count[f[n], p_ /; Max[p] == 2*Min[p]], {n, 0, z}] (* A241035 *)
    Table[Count[f[n], p_ /; Max[p] == 3*Min[p]], {n, 0, z}] (* A241063 *)
    Table[Count[f[n], p_ /; Max[p] == 4*Min[p]], {n, 0, z}] (* A241069 *)
    Table[Count[f[n], p_ /; Max[p] == 5*Min[p]], {n, 0, z}] (* A241272 *)
    Table[Count[f[n], p_ /; Max[p] == 6*Min[p]], {n, 0, z}] (* A241273 *)

A241069 Number of partitions p of n into distinct parts such that max(p) = 4*min(p).

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 2, 0, 0, 1, 1, 2, 1, 2, 1, 3, 4, 3, 3, 3, 4, 6, 6, 4, 6, 5, 8, 8, 9, 9, 10, 13, 11, 13, 15, 17, 20, 21, 21, 24, 25, 29, 30, 33, 35, 40, 44, 44, 49, 51, 56, 61, 66, 69, 77, 82, 91, 95, 102, 106, 116, 127, 134, 147, 157, 168, 182
Offset: 0

Views

Author

Clark Kimberling, Apr 18 2014

Keywords

Examples

			a(10) counts these 2 partitions:  82, 4321.

Crossrefs

Cf. A241035, A241063, A241272, A241273.

Programs

  • Mathematica
    z = 40; f[n_] := f[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
    Table[Count[f[n], p_ /; Max[p] == 2*Min[p]], {n, 0, z}] (* A241035 *)
    Table[Count[f[n], p_ /; Max[p] == 3*Min[p]], {n, 0, z}] (* A241063 *)
    Table[Count[f[n], p_ /; Max[p] == 4*Min[p]], {n, 0, z}] (* A241069 *)
    Table[Count[f[n], p_ /; Max[p] == 5*Min[p]], {n, 0, z}] (* A241272 *)
    Table[Count[f[n], p_ /; Max[p] == 6*Min[p]], {n, 0, z}] (* A241273 *)

A241272 Number of partitions p of n into distinct parts such that max(p) = 5*min(p).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 2, 1, 0, 2, 1, 1, 2, 2, 2, 3, 3, 4, 6, 5, 5, 7, 7, 9, 11, 10, 11, 12, 12, 14, 18, 18, 18, 21, 21, 24, 27, 30, 30, 36, 37, 42, 47, 49, 54, 60, 64, 71, 81, 83, 91, 100, 107, 116, 129, 136, 147, 159, 172, 184, 200, 213, 228
Offset: 0

Views

Author

Clark Kimberling, Apr 18 2014

Keywords

Examples

			a(12) counts these 2 partitions:  {10,2}, {5,4,2,1}.

Crossrefs

Cf. A241035, A241063, A241269, A241273.

Programs

  • Mathematica
    z = 40; f[n_] := f[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
Table[Count[f[n], p_ /; Max[p] == 2*Min[p]], {n, 0, z}] (* A241035 *)
Table[Count[f[n], p_ /; Max[p] == 3*Min[p]], {n, 0, z}] (* A241063 *)
Table[Count[f[n], p_ /; Max[p] == 4*Min[p]], {n, 0, z}] (* A241069 *)
Table[Count[f[n], p_ /; Max[p] == 5*Min[p]], {n, 0, z}] (* A241272 *)
Table[Count[f[n], p_ /; Max[p] == 6*Min[p]], {n, 0, z}] (* A241273 *)

A241273 Number of partitions p of n into distinct parts such that max(p) = 6*min(p).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 2, 1, 3, 1, 2, 2, 2, 2, 1, 4, 2, 3, 3, 5, 5, 6, 8, 8, 9, 10, 13, 14, 16, 18, 20, 20, 24, 25, 28, 31, 36, 37, 40, 42, 46, 51, 55, 62, 65, 72, 76, 83, 89, 98, 107, 117, 126, 139, 149, 163, 177, 195, 208, 226, 247, 267, 291
Offset: 0

Views

Author

Clark Kimberling, Apr 18 2014

Keywords

Examples

			a(14) counts these 3 partitions:  {12,2}, {6,5,2,1}, {6,4,3,1}.

Crossrefs

Cf. A241035, A241063, A241269, A241272.

Programs

  • Mathematica
    z = 40; f[n_] := f[n] = Select[IntegerPartitions[n], Max[Length /@ Split@#] == 1 &];
Table[Count[f[n], p_ /; Max[p] == 2*Min[p]], {n, 0, z}] (* A241035 *)
Table[Count[f[n], p_ /; Max[p] == 3*Min[p]], {n, 0, z}] (* A241063 *)
Table[Count[f[n], p_ /; Max[p] == 4*Min[p]], {n, 0, z}] (* A241069 *)
Table[Count[f[n], p_ /; Max[p] == 5*Min[p]], {n, 0, z}] (* A241272 *)
Table[Count[f[n], p_ /; Max[p] == 6*Min[p]], {n, 0, z}] (* A241273 *)

A361854 Number of strict integer partitions of n such that (length) * (maximum) = 2n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 2, 0, 1, 2, 2, 0, 5, 0, 6, 3, 5, 0, 11, 6, 8, 7, 10, 0, 36, 0, 14, 16, 16, 29, 43, 0, 21, 36, 69, 0, 97, 0, 35, 138, 33, 0, 150, 61, 137, 134, 74, 0, 231, 134, 265, 229, 56, 0, 650, 0, 65, 749, 267, 247, 533, 0, 405, 565
Offset: 1

Views

Author

Gus Wiseman, Mar 29 2023

Keywords

Comments

Also strict partitions satisfying (maximum) = 2*(mean).
These are strict partitions where both the diagram and its complement (see example) have size n.

Examples

			The a(n) strict partitions for selected n (A..E = 10..14):
  n=9:  n=12:  n=14:  n=15:  n=16:  n=18:  n=20:  n=21:  n=22:
--------------------------------------------------------------
  621   831    7421   A32    8431   C42    A532   E43    B542
        6321          A41    8521   C51    A541   E52    B632
                                    9432   A631   E61    B641
                                    9531   A721          B731
                                    9621   85421         B821
                                           86321
The a(20) = 6 strict partitions are: (10,7,2,1), (10,6,3,1), (10,5,4,1), (10,5,3,2), (8,6,3,2,1), (8,5,4,2,1).
The strict partition y = (8,5,4,2,1) has diagram:
  o o o o o o o o
  o o o o o . . .
  o o o o . . . .
  o o . . . . . .
  o . . . . . . .
Since the partition and its complement (shown in dots) have the same size, y is counted under a(20).

Crossrefs

For minimum instead of mean we have A241035, non-strict A118096.
For length instead of mean we have A241087, non-strict A237753.
For median instead of mean we have A361850, non-strict A361849.
The non-strict version is A361853.
These partitions have ranks A361855 /\ A005117.
A000041 counts integer partitions, strict A000009.
A008284 counts partitions by length, A058398 by mean.
A008289 counts strict partitions by length.
A102627 counts strict partitions with integer mean, non-strict A067538.
A116608 counts partitions by number of distinct parts.
A268192 counts partitions by complement size, ranks A326844.
Cf. A111907, A237755, A240850, A326849 A359897, A360068, A360071, A360243, A361848, A361851, A361852, A361906.

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n], UnsameQ@@#&&Length[#]*Max@@#==2n&]],{n,30}]

A361850 Number of strict integer partitions of n such that the maximum is twice the median.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 2, 0, 2, 1, 3, 3, 4, 2, 5, 4, 7, 8, 10, 6, 11, 11, 15, 16, 21, 18, 25, 23, 28, 32, 40, 40, 51, 51, 58, 60, 73, 75, 93, 97, 113, 123, 139, 141, 164, 175, 199, 217, 248, 263, 301, 320, 356, 383, 426, 450, 511, 551, 613, 664, 737
Offset: 1

Views

Author

Gus Wiseman, Apr 02 2023

Keywords

Comments

The median of a multiset is either the middle part (for odd length), or the average of the two middle parts (for even length).

Examples

			The a(7) = 1 through a(20) = 4 strict partitions (A..C = 10..12):
  421  .  .  631  632   .  841   842  843   A51    A52    A53   A54   C62
                  5321     6421       7431  7432   8531   8532  C61   9542
                                      7521  64321  8621         9541  9632
                                                   65321        9631  85421
                                                                9721
The partition (7,4,3,1) has maximum 7 and median 7/2, so is counted under a(15).
The partition (8,6,2,1) has maximum 8 and median 4, so is counted under a(17).

Crossrefs

For minimum instead of median we have A241035, non-strict A237824.
For length instead of median we have A241087, non-strict A237755.
The non-strict version is A361849, ranks A361856.
The non-strict complement is counted by A361857, ranks A361867.
A000041 counts integer partitions, strict A000009.
A000975 counts subsets with integer median.
A008284 counts partitions by length, A058398 by mean.
A325347 counts partitions with integer median, complement A307683.
A359893 and A359901 count partitions by median, odd-length A359902.
A359907 counts strict partitions with integer median
A360005 gives median of prime indices (times two), distinct A360457.
Cf. A027193, A067659, A079309, A111907, A116608, A359897, A359908, A360952, A361851, A361858, A361859, A361860.

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n],UnsameQ@@#&&Max@@#==2*Median[#]&]],{n,30}]
Showing 1-9 of 9 results.

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