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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A305732 Heinz numbers of reducible integer partitions. Numbers n > 1 that are prime or whose prime indices are relatively prime and such that A181819(n) is already in the sequence.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 26, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78
Offset: 1

Views

Author

Gus Wiseman, Jun 22 2018

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). A prime index of n is a number m such that prime(m) divides n. A multiset m whose distinct elements are m_1, m_2, ..., m_k with multiplicities y_1, y_2, ..., y_k is reducible if either m is of size 1 or gcd(m_1,...,m_k) = 1 and the multiset {y_1,...,y_k} is also reducible.

Examples

			60 has relatively prime prime indices {1,1,2,3} with multiplicities {1,1,2} corresponding to A181819(90) = 12. 12 has relatively prime prime indices {1,1,2} with multiplicities {1,2} corresponding to A181819(12) = 6. 6 has relatively prime prime indices {1,2} with multiplicities {1,1} corresponding to A181819(6) = 4. 4 has relatively prime prime indices {1,1} with multiplicities {2} corresponding to A181819(4) = 3. 3 is prime, so we conclude that 60 belongs to the sequence.
		

Crossrefs

Programs

  • Mathematica
    rdzQ[n_]:=And[n>1,Or[PrimeQ[n],And[rdzQ[Times@@Prime/@FactorInteger[n][[All,2]]],GCD@@PrimePi/@FactorInteger[n][[All,1]]==1]]];
    Select[Range[50],rdzQ]

A320810 Number of non-isomorphic multiset partitions of weight n whose part-sizes have a common divisor > 1.

Original entry on oeis.org

0, 2, 3, 12, 7, 84, 15, 410, 354, 3073, 56, 28300, 101, 210036, 126839, 2070047, 297, 25295952, 490, 269662769, 89071291, 3449056162, 1255, 51132696310, 400625539, 713071048480, 145126661415, 11351097702297, 4565, 199926713003444, 6842, 3460838122540969
Offset: 1

Views

Author

Gus Wiseman, Nov 15 2018

Keywords

Comments

Also the number of nonnegative integer matrices up to row and column permutations with sum of elements equal to n and no zero rows or columns, in which the column sums are not relatively prime.
Also the number of non-isomorphic multiset partitions of weight n in which the multiset union of the parts is periodic, where a multiset is periodic if its multiplicities have a common divisor > 1.
The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.

Examples

			Non-isomorphic representatives of the a(2) = 1 through a(5) = 7 multiset partitions whose part-sizes have a common divisor:
  {{1,1}}  {{1,1,1}}  {{1,1,1,1}}    {{1,1,1,1,1}}
  {{1,2}}  {{1,2,2}}  {{1,1,2,2}}    {{1,1,2,2,2}}
           {{1,2,3}}  {{1,2,2,2}}    {{1,2,2,2,2}}
                      {{1,2,3,3}}    {{1,2,2,3,3}}
                      {{1,2,3,4}}    {{1,2,3,3,3}}
                      {{1,1},{1,1}}  {{1,2,3,4,4}}
                      {{1,1},{2,2}}  {{1,2,3,4,5}}
                      {{1,2},{1,2}}
                      {{1,2},{2,2}}
                      {{1,2},{3,3}}
                      {{1,2},{3,4}}
                      {{1,3},{2,3}}
Non-isomorphic representatives of the a(2) = 1 through a(5) = 7 multiset partitions with periodic multiset union:
  {{1,1}}    {{1,1,1}}      {{1,1,1,1}}        {{1,1,1,1,1}}
  {{1},{1}}  {{1},{1,1}}    {{1,1,2,2}}        {{1},{1,1,1,1}}
             {{1},{1},{1}}  {{1},{1,1,1}}      {{1,1},{1,1,1}}
                            {{1,1},{1,1}}      {{1},{1},{1,1,1}}
                            {{1},{1,2,2}}      {{1},{1,1},{1,1}}
                            {{1,1},{2,2}}      {{1},{1},{1},{1,1}}
                            {{1,2},{1,2}}      {{1},{1},{1},{1},{1}}
                            {{1},{1},{1,1}}
                            {{1},{1},{2,2}}
                            {{1},{2},{1,2}}
                            {{1},{1},{1},{1}}
                            {{1},{1},{2},{2}}
		

Crossrefs

Programs

  • PARI
    \\ See links in A339645 for combinatorial species functions.
    seq(n)={my(A=symGroupSeries(n));Vec(OgfSeries(sCartProd(sExp(A), -sum(d=2, n, moebius(d) * (-1 + sExp(O(x*x^n) + sum(i=1, n\d, polcoef(A,i*d)*x^(i*d)))) ))), -n)} \\ Andrew Howroyd, Jan 17 2023

Formula

a(n) = A007716(n) - A321283(n). - Andrew Howroyd, Jan 17 2023

Extensions

Terms a(11) and beyond from Andrew Howroyd, Jan 17 2023

A319162 Number of periodic integer partitions of n whose multiplicities are aperiodic, meaning the multiplicities of these multiplicities are relatively prime.

Original entry on oeis.org

0, 1, 1, 2, 1, 3, 1, 4, 2, 6, 1, 9, 1, 12, 6, 16, 1, 27, 1, 33, 12, 46, 1, 70, 5, 84, 22, 110, 1, 172, 1, 188, 46, 251, 15, 366, 1, 418, 84, 540, 1, 775, 1, 863, 162, 1095, 1, 1535, 11, 1750, 251, 2154, 1, 2963, 49, 3323, 418, 4106, 1, 5567
Offset: 1

Views

Author

Gus Wiseman, Sep 12 2018

Keywords

Examples

			The a(12) = 9 partitions:
  (66),
  (444), (441111),
  (3333), (33111111),
  (222222), (222111111), (2211111111),
  (111111111111).
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n],And[GCD@@Sort[Length/@Split[#]]>1,GCD@@Length/@Split[Sort[Length/@Split[#]]]==1]&]],{n,30}]

A319164 Number of integer partitions of n that are neither relatively prime nor aperiodic.

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 2, 1, 2, 0, 5, 0, 2, 2, 5, 0, 6, 0, 9, 2, 2, 0, 17, 1, 2, 3, 17, 0, 18, 0, 22, 2, 2, 2, 48, 0, 2, 2, 48, 0, 34, 0, 58, 11, 2, 0, 111, 1, 14, 2, 103, 0, 65, 2, 141, 2, 2, 0, 264, 0, 2, 19, 231, 2, 116, 0, 299, 2, 42
Offset: 1

Views

Author

Gus Wiseman, Sep 12 2018

Keywords

Comments

A partition is aperiodic if its multiplicities are relatively prime.

Examples

			The a(24) = 17 integer partitions:
  (12,12),
  (8,8,8),
  (6,6,6,6), (8,8,4,4), (9,9,3,3), (10,10,2,2),
  (4,4,4,4,4,4), (6,6,3,3,3,3), (6,6,4,4,2,2), (6,6,6,2,2,2), (8,8,2,2,2,2),
  (3,3,3,3,3,3,3,3), (4,4,4,4,2,2,2,2), (6,6,2,2,2,2,2,2),
  (4,4,4,2,2,2,2,2,2),
  (4,4,2,2,2,2,2,2,2,2),
  (2,2,2,2,2,2,2,2,2,2,2,2).
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n],And[GCD@@#>1,GCD@@Length/@Split[#]>1]&]],{n,30}]

A305733 Heinz numbers of irreducible integer partitions. Nonprime numbers whose prime indices have a common divisor > 1 or such that A181819(n) is already in the sequence.

Original entry on oeis.org

1, 9, 21, 25, 27, 36, 39, 49, 57, 63, 65, 81, 87, 91, 100, 111, 115, 117, 121, 125, 129, 133, 144, 147, 159, 169, 171, 183, 185, 189, 196, 203, 213, 216, 225, 235, 237, 243, 247, 259, 261, 267, 273, 289, 299, 301, 303, 305, 319, 321, 324, 325, 333, 339, 343
Offset: 1

Views

Author

Gus Wiseman, Jun 22 2018

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). A prime index of n is a number m such that prime(m) divides n. A multiset m whose distinct elements are m_1, m_2, ..., m_k with multiplicities y_1, y_2, ..., y_k is reducible if either m is of size 1 or gcd(m_1, ..., m_k) = 1 and the multiset {y_1, ..., y_k} is also reducible.

Crossrefs

Programs

  • Mathematica
    rdzQ[n_]:=And[n>1,Or[PrimeQ[n],And[rdzQ[Times@@Prime/@FactorInteger[n][[All,2]]],GCD@@PrimePi/@FactorInteger[n][[All,1]]==1]]];
    Select[Range[50],!rdzQ[#]&]

A319160 Number of integer partitions of n whose multiplicities appear with relatively prime multiplicities.

Original entry on oeis.org

1, 2, 2, 4, 5, 7, 11, 16, 22, 31, 45, 58, 83, 108, 142, 188, 250, 315, 417, 528, 674, 861, 1094, 1363, 1724, 2152, 2670, 3311, 4105, 5021, 6193, 7561, 9216, 11219, 13614, 16419, 19886, 23920, 28733, 34438, 41272, 49184, 58746, 69823, 82948, 98380, 116567
Offset: 1

Views

Author

Gus Wiseman, Sep 12 2018

Keywords

Comments

From Gus Wiseman, Jul 11 2023: (Start)
A partition is aperiodic (A000837) if its multiplicities are relatively prime. This sequence counts partitions whose multiplicities are aperiodic.
For example:
- The multiplicities of (5,3) are (1,1), with multiplicities (2), with common divisor 2, so it is not counted under a(8).
- The multiplicities of (3,2,2,1) are (2,1,1), with multiplicities (2,1), which are relatively prime, so it is counted under a(8).
- The multiplicities of (3,3,1,1) are (2,2), with multiplicities (2), with common divisor 2, so it is not counted under a(8).
- The multiplicities of (4,4,4,3,3,3,2,1) are (3,3,1,1), with multiplicities (2,2), which have common divisor 2, so it is not counted under a(24).
(End)

Examples

			The a(8) = 16 partitions:
  (8),
  (44),
  (332), (422), (611),
  (2222), (3221), (4211), (5111),
  (22211), (32111), (41111),
  (221111), (311111),
  (2111111),
  (11111111).
Missing from this list are: (53), (62), (71), (431), (521), (3311).
		

Crossrefs

These partitions have ranks A319161.
For distinct instead of relatively prime multiplicities we have A325329.

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n], GCD@@Length/@Split[Sort[Length/@Split[#]]]==1&]],{n,30}]

A319810 Number of fully periodic integer partitions of n.

Original entry on oeis.org

1, 2, 2, 3, 2, 5, 2, 5, 4, 6, 2, 11, 2, 8, 7, 11, 2, 17, 2, 18, 9, 15, 2, 32, 5, 22, 12, 34, 2, 54, 2, 49, 16, 51, 10, 94, 2, 77, 23, 112, 2, 152, 2, 148, 47, 165, 2, 258, 7, 247, 52, 286, 2, 400, 17, 402, 78, 439, 2, 657, 2, 594, 131, 711, 24
Offset: 1

Views

Author

Gus Wiseman, Sep 28 2018

Keywords

Comments

An integer partition is fully periodic iff either it is a singleton or it is a periodic partition (meaning its multiplicities have a common divisor > 1) with fully periodic multiplicities.

Examples

			The a(12) = 11 fully periodic integer partitions:
  (12)
  (6,6)
  (4,4,4)
  (5,5,1,1)
  (4,4,2,2)
  (3,3,3,3)
  (3,3,3,1,1,1)
  (3,3,2,2,1,1)
  (2,2,2,2,2,2)
  (2,2,2,2,1,1,1,1)
  (1,1,1,1,1,1,1,1,1,1,1,1)
Periodic partitions missing from this list are:
  (4,4,1,1,1,1)
  (3,3,1,1,1,1,1,1)
  (2,2,2,1,1,1,1,1,1)
  (2,2,1,1,1,1,1,1,1,1)
The first non-uniform fully periodic partition is (4,4,3,3,2,2,2,2,1,1,1,1).
The first periodic integer partition that is not fully periodic is (2,2,1,1,1,1).
		

Crossrefs

Programs

  • Mathematica
    totperQ[m_]:=Or[Length[m]==1,And[GCD@@Length/@Split[Sort[m]]>1,totperQ[Sort[Length/@Split[Sort[m]]]]]];
    Table[Length[Select[IntegerPartitions[n],totperQ]],{n,30}]

A305564 Number of finite sets of relatively prime positive integers with least common multiple n.

Original entry on oeis.org

1, 1, 1, 2, 1, 7, 1, 4, 2, 7, 1, 32, 1, 7, 7, 8, 1, 32, 1, 32, 7, 7, 1, 136, 2, 7, 4, 32, 1, 193, 1, 16, 7, 7, 7, 322, 1, 7, 7, 136, 1, 193, 1, 32, 32, 7, 1, 560, 2, 32, 7, 32, 1, 136, 7, 136, 7, 7, 1, 3464, 1, 7, 32, 32, 7, 193, 1, 32, 7, 193, 1, 2852, 1, 7
Offset: 1

Views

Author

Gus Wiseman, Jun 05 2018

Keywords

Examples

			The a(6) = 7 sets are {1,6}, {2,3}, {1,2,3}, {1,2,6}, {1,3,6}, {2,3,6}, {1,2,3,6}.
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[Rest[Subsets[Divisors[n]]],And[GCD@@#==1,LCM@@#==n]&]],{n,100}]

A305565 Regular triangle where T(n,k) is the number of finite sets of positive integers with least common multiple n and greatest common divisor k.

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 2, 1, 0, 1, 1, 0, 0, 0, 1, 7, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 4, 2, 0, 1, 0, 0, 0, 1, 2, 0, 1, 0, 0, 0, 0, 0, 1, 7, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 32, 7, 2, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Gus Wiseman, Jun 05 2018

Keywords

Examples

			The T(12,2) = 7 sets are {2,12}, {4,6}, {2,4,6}, {2,4,12}, {2,6,12}, {4,6,12}, {2,4,6,12}.
Triangle begins:
   1
   1  1
   1  0  1
   2  1  0  1
   1  0  0  0  1
   7  1  1  0  0  1
   1  0  0  0  0  0  1
   4  2  0  1  0  0  0  1
   2  0  1  0  0  0  0  0  1
   7  1  0  0  1  0  0  0  0  1
   1  0  0  0  0  0  0  0  0  0  1
  32  7  2  1  0  1  0  0  0  0  0  1
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[Subsets[Divisors[n]],And[GCD@@#==k,LCM@@#==n]&]],{n,20},{k,n}]

Formula

If k divides n then T(n,k) = T(n/k,1) = A305564(n/k); otherwise T(n,k) = 0.

A305731 Number of irreducible integer partitions of n.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 4, 0, 6, 3, 12, 0, 21, 1, 30, 19, 43, 10, 82, 20, 103, 68, 152, 58, 236, 102, 301, 196, 413, 205, 653, 310, 788, 580, 1115, 718, 1649, 1006, 2149, 1714, 3018, 2247, 4502, 3389, 6036, 5509, 8647, 7601, 12678, 11310, 17541
Offset: 0

Views

Author

Gus Wiseman, Jun 22 2018

Keywords

Comments

A multiset m whose distinct elements are m_1, m_2, ..., m_k with multiplicities y_1, y_2, ..., y_k is irreducible if m is of size > 1 and either gcd(m_1, ..., m_k) > 1 or the multiset {y_1, ..., y_k} is irreducible.

Examples

			The a(6) = 4 irreducible partitions are (42), (33), (222), (2211).
		

Crossrefs

Programs

  • Mathematica
    ptnredQ[y_]:=Or[Length[y]==1,And[GCD@@y==1,ptnredQ[Sort[Length/@Split[y],Greater]]]];
    Table[Length[Select[IntegerPartitions[n],!ptnredQ[#]&]],{n,20}]
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