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.

A325336 Triangle read by rows where T(n,k) is the number of integer partitions of n with adjusted frequency depth k whose parts cover an initial interval of positive integers.

Original entry on oeis.org

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

Views

Author

Gus Wiseman, May 01 2019

Keywords

Comments

The adjusted frequency depth of an integer partition (A325280) is 0 if the partition is empty, and otherwise it is 1 plus the number of times one must take the multiset of multiplicities to reach a singleton. For example, the partition (32211) has adjusted frequency depth 5 because we have: (32211) -> (221) -> (21) -> (11) -> (2).

Examples

			Triangle begins:
  1
  0  1
  0  0  1
  0  0  1  1
  0  0  1  0  1
  0  0  1  0  2  0
  0  0  1  2  1  0  0
  0  0  1  0  3  1  0  0
  0  0  1  0  3  2  0  0  0
  0  0  1  1  3  3  0  0  0  0
  0  0  1  1  5  3  0  0  0  0  0
  0  0  1  0  8  3  0  0  0  0  0  0
  0  0  1  2  6  6  0  0  0  0  0  0  0
  0  0  1  0 13  4  0  0  0  0  0  0  0  0
  0  0  1  0 12  8  1  0  0  0  0  0  0  0  0
  0  0  1  2 14  7  3  0  0  0  0  0  0  0  0  0
  0  0  1  0 17 11  3  0  0  0  0  0  0  0  0  0  0
  0  0  1  0 22  7  8  0  0  0  0  0  0  0  0  0  0  0
  0  0  1  2 17 16 10  0  0  0  0  0  0  0  0  0  0  0  0
  0  0  1  0 28 10 15  0  0  0  0  0  0  0  0  0  0  0  0  0
  0  0  1  1 29 13 20  0  0  0  0  0  0  0  0  0  0  0  0  0  0
Row 15 counts the following partitions:
  111111111111111  54321       433221          333321        4322211
                   2222211111  443211          3332211       4332111
                               3322221         33222111      43221111
                               22222221        322221111
                               32222211        332211111
                               33321111        432111111
                               222222111       321111111111
                               3222111111
                               3321111111
                               22221111111
                               32211111111
                               222111111111
                               2211111111111
                               21111111111111
		

Crossrefs

Row sums are A000009.
Column k = 3 is A325334.
Column k = 4 is A325335.

Programs

  • Mathematica
    normQ[m_]:=Or[m=={},Union[m]==Range[Max[m]]];
    fdadj[ptn_List]:=If[ptn=={},0,Length[NestWhileList[Sort[Length/@Split[#1]]&,ptn,Length[#1]>1&]]];
    Table[Length[Select[IntegerPartitions[n],normQ[#]&&fdadj[#]==k&]],{n,0,30},{k,0,n}]
  • PARI
    depth(p)={if(!#p, 0, my(r=1); while(#p > 1, my(L=List(), k=0); for(i=1, #p, if(i==#p||p[i]<>p[i+1], listput(L,i-k); k=i)); listsort(L); p=L; r++); r)}
    isok(p)={if(#p, for(i=1, #p, if(p[i]-1 > if(i>1, p[i-1], 0), return(0)))); 1}
    row(n)={my(v=vector(1+n)); forpart(p=n, if(isok(p), v[1+depth(Vec(p))]++)); v}
    { for(n=0, 10, print(row(n))) } \\ Andrew Howroyd, Jan 18 2023

A325374 Numbers with adjusted frequency depth 3 whose prime indices cover an initial interval of positive integers.

Original entry on oeis.org

6, 30, 36, 210, 216, 900, 1296, 2310, 7776, 27000, 30030, 44100, 46656, 279936, 510510, 810000, 1679616, 5336100, 9261000, 9699690, 10077696, 24300000, 60466176, 223092870, 362797056, 729000000, 901800900, 1944810000, 2176782336, 6469693230, 12326391000
Offset: 1

Views

Author

Gus Wiseman, May 02 2019

Keywords

Comments

The adjusted frequency depth (A323014) of a positive integer n is 0 if n = 1, and otherwise it is 1 plus the number of times one must apply A181819 to reach a prime number, where A181819(k = p^i*...*q^j) = prime(i)*...*prime(j) = product of primes indexed by the prime exponents of k. For example, 180 has adjusted frequency depth 5 because we have: 180 -> 18 -> 6 -> 4 -> 3.
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k), so these are Heinz numbers of integer partitions with adjusted frequency depth 3 whose parts cover an initial interval of positive integers. The enumeration of these partitions by sum is given by A325334.
The terms are the primorial numbers (A002110) above 2 and all their powers. - Amiram Eldar, May 08 2019

Examples

			The sequence of terms together with their prime indices begins:
      6: {1,2}
     30: {1,2,3}
     36: {1,1,2,2}
    210: {1,2,3,4}
    216: {1,1,1,2,2,2}
    900: {1,1,2,2,3,3}
   1296: {1,1,1,1,2,2,2,2}
   2310: {1,2,3,4,5}
   7776: {1,1,1,1,1,2,2,2,2,2}
  27000: {1,1,1,2,2,2,3,3,3}
  30030: {1,2,3,4,5,6}
  44100: {1,1,2,2,3,3,4,4}
  46656: {1,1,1,1,1,1,2,2,2,2,2,2}
		

Crossrefs

Programs

  • Mathematica
    normQ[n_Integer]:=Or[n==1,PrimePi/@First/@FactorInteger[n]==Range[PrimeNu[n]]];
    fdadj[n_Integer]:=If[n==1,0,Length[NestWhileList[Times@@Prime/@Last/@FactorInteger[#1]&,n,!PrimeQ[#1]&]]];
    Select[Range[10000],normQ[#]&&fdadj[#]==3&]

A325335 Number of integer partitions of n with adjusted frequency depth 4 whose parts cover an initial interval of positive integers.

Original entry on oeis.org

0, 0, 0, 0, 1, 2, 1, 3, 3, 3, 5, 8, 6, 13, 12, 14, 17, 22, 17, 28, 29, 30, 38, 50, 46, 67, 64, 75, 81, 104, 99, 127, 128, 150, 155, 201, 189, 236, 244, 293, 302, 363, 372, 437, 457, 548, 547, 638, 671, 754, 809, 922, 947, 1074, 1144, 1290, 1342, 1515, 1574
Offset: 0

Views

Author

Gus Wiseman, May 01 2019

Keywords

Comments

The adjusted frequency depth of an integer partition (A325280) is 0 if the partition is empty, and otherwise it is 1 plus the number of times one must take the multiset of multiplicities to reach a singleton. For example, the partition (32211) has adjusted frequency depth 5 because we have: (32211) -> (221) -> (21) -> (11) -> (2).
The Heinz numbers of these partitions are given by A325387.

Examples

			The a(4) = 1 through a(10) = 5 partitions:
  (211)  (221)   (21111)  (2221)    (22211)    (22221)     (222211)
         (2111)           (22111)   (221111)   (2211111)   (322111)
                          (211111)  (2111111)  (21111111)  (2221111)
                                                           (22111111)
                                                           (211111111)
		

Crossrefs

Programs

  • Mathematica
    normQ[m_]:=Or[m=={},Union[m]==Range[Max[m]]];
    fdadj[ptn_List]:=If[ptn=={},0,Length[NestWhileList[Sort[Length/@Split[#1]]&,ptn,Length[#1]>1&]]];
    Table[Length[Select[IntegerPartitions[n],normQ[#]&&fdadj[#]==4&]],{n,0,30}]

A325646 Number of separable partitions of n in which the number of distinct (repeatable) parts is 2.

Original entry on oeis.org

0, 0, 1, 2, 4, 4, 7, 8, 9, 11, 13, 14, 16, 18, 18, 22, 22, 25, 25, 29, 28, 32, 31, 38, 34, 39, 38, 44, 40, 49, 43, 52, 48, 53, 50, 63, 52, 60, 58, 69, 58, 73, 61, 74, 70, 74, 67, 90, 71, 84, 78, 89, 76, 97, 82, 100, 88, 95, 85, 119
Offset: 1

Views

Author

Clark Kimberling, May 16 2019

Keywords

Comments

A partition is separable if there is an ordering of its parts in which no consecutive parts are identical. See A325534 for a guide to related sequences.

Examples

			a(6) counts these 4 partitions:  [5,1], [4,2], [1,4,1], [2,1,2,1].
		

Crossrefs

Programs

  • Mathematica
    (separable=Table[Map[# [[1]]&,Select[Map[{#,Quotient[(1+Length[#]),Max[Map[Length,Split[#]]]]}&,IntegerPartitions[nn]],#[[2]]>1&]],{nn,35}]);
    Map[Length[Select[Map[{#,Length[Union[#]]}&,#],#[[2]]==2&]]&,separable]
    (* Peter J. C. Moses, May 08 2019 *)

A325712 Number of separable partitions of n in which the number of distinct (repeatable) parts <= 3.

Original entry on oeis.org

1, 1, 2, 3, 5, 6, 10, 14, 19, 25, 35, 44, 56, 68, 87, 102, 124, 142, 171, 197, 225, 254, 294, 326, 370, 408, 451, 505, 553, 604, 661, 726, 772, 854, 916, 989, 1054, 1151, 1199, 1320, 1376, 1492, 1555, 1694, 1736, 1903, 1952, 2113, 2170, 2360, 2387, 2610
Offset: 1

Views

Author

Clark Kimberling, May 16 2019

Keywords

Comments

A partition is separable if there is an ordering of its parts in which no consecutive parts are identical. See A325534 for a guide to related sequences.

Crossrefs

Programs

  • Mathematica
    (separable=Table[Map[#[[1]]&,Select[Map[{#,Quotient[(1+Length[#]),Max[Map[Length,Split[#]]]]}&,IntegerPartitions[nn]],#[[2]]>1&]],{nn,35}]);
    Map[Length[Select[Map[{#,Length[Union[#]]}&,#],#[[2]]<=3&]]&,separable]
    (* Peter J. C. Moses, May 08 2019 *)

A325647 Number of separable partitions of n in which the number of distinct (repeatable) parts is 3.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 2, 5, 9, 13, 21, 29, 39, 49, 68, 79, 101, 116, 145, 167, 196, 221, 262, 287, 335, 368, 412, 460, 512, 554, 617, 673, 723, 800, 865, 925, 1001, 1090, 1140, 1250, 1317, 1418, 1493, 1619, 1665, 1828, 1884, 2022, 2098, 2275, 2308, 2520, 2564
Offset: 1

Views

Author

Clark Kimberling, May 16 2019

Keywords

Comments

A partition is separable if there is an ordering of its parts in which no consecutive parts are identical. See A325646 for a guide to related sequences.

Examples

			a(8) counts these 5 partitions:  [5,2,1], [4,3,1], [1,4,1,2], [2,3,2,1], [1,3,1,2,1].
		

Crossrefs

Programs

  • Mathematica
    (separable=Table[Map[#[[1]]&,Select[Map[{#,Quotient[(1+Length[#]),Max[Map[Length,Split[#]]]]}&,IntegerPartitions[nn]],#[[2]]>1&]],{nn,35}]);
    Map[Length[Select[Map[{#,Length[Union[#]]}&,#],#[[2]]==3&]]&,separable]
    (* Peter J. C. Moses, May 08 2019 *)

A325711 Number of separable partitions of n in which the number of distinct (repeatable) parts <= 2.

Original entry on oeis.org

1, 1, 2, 3, 5, 5, 8, 9, 10, 12, 14, 15, 17, 19, 19, 23, 23, 26, 26, 30, 29, 33, 32, 39, 35, 40, 39, 45, 41, 50, 44, 53, 49, 54, 51, 64, 53, 61, 59, 70, 59, 74, 62, 75, 71, 75, 68, 91, 72, 85, 79, 90, 77, 98, 83, 101, 89, 96, 86, 120
Offset: 1

Views

Author

Clark Kimberling, May 16 2019

Keywords

Comments

A partition is separable if there is an ordering of its parts in which no consecutive parts are identical. See A325534 for a guide to related sequences.

Examples

			a(6) counts these 5 partitions:  [6], [5,1], [4,2], [1,4,1], [2,1,2,1].
		

Crossrefs

Programs

  • Mathematica
    (separable=Table[Map[#[[1]]&,Select[Map[{#,Quotient[(1+Length[#]),Max[Map[Length,Split[#]]]]}&,IntegerPartitions[nn]],#[[2]]>1&]],{nn,35}]);
    Map[Length[Select[Map[{#,Length[Union[#]]}&,#],#[[2]]<=2&]]&,separable]
    (* Peter J. C. Moses, May 08 2019 *)

A325713 Number of separable partitions of n in which the number of distinct (repeatable) parts <= 4.

Original entry on oeis.org

1, 1, 2, 3, 5, 6, 10, 14, 19, 26, 37, 49, 66, 87, 115, 150, 193, 244, 309, 387, 479, 585, 714, 860, 1032, 1226, 1454, 1697, 1991, 2304, 2672, 3060, 3518, 3981, 4541, 5121, 5782, 6462, 7265, 8057, 9000, 9938, 11031, 12131, 13384, 14634, 16085, 17534, 19161
Offset: 1

Views

Author

Clark Kimberling, May 16 2019

Keywords

Comments

A partition is separable if there is an ordering of its parts in which no consecutive parts are identical. See A325534 for a guide to related sequences.

Crossrefs

Programs

  • Mathematica
    (separable=Table[Map[#[[1]]&,Select[Map[{#,Quotient[(1+Length[#]),Max[Map[Length,Split[#]]]]}&,IntegerPartitions[nn]],#[[2]]>1&]],{nn,35}]);
    Map[Length[Select[Map[{#,Length[Union[#]]}&,#],#[[2]]<=4&]]&,separable]
    (* Peter J. C. Moses, May 08 2019 *)

A325714 Number of separable partitions of n in which the number of distinct (repeatable) parts <= 5.

Original entry on oeis.org

1, 1, 2, 3, 5, 6, 10, 14, 19, 26, 37, 49, 66, 87, 116, 152, 198, 254, 329, 422, 535, 676, 853, 1067, 1329, 1645, 2025, 2486, 3027, 3673, 4432, 5329, 6361, 7580, 8978, 10591, 12439, 14563, 16962, 19717, 22801, 26295, 30212, 34612, 39531, 45006, 51100, 57839
Offset: 1

Views

Author

Clark Kimberling, May 16 2019

Keywords

Comments

A partition is separable if there is an ordering of its parts in which no consecutive parts are identical. See A325534 for a guide to related sequences.

Crossrefs

Programs

  • Mathematica
    (separable=Table[Map[#[[1]]&,Select[Map[{#,Quotient[(1+Length[#]),Max[Map[Length,Split[#]]]]}&,IntegerPartitions[nn]],#[[2]]>1&]],{nn,35}]);
    Map[Length[Select[Map[{#,Length[Union[#]]}&,#],#[[2]]<=5&]]&,separable]
    (* Peter J. C. Moses, May 08 2019 *)

A325715 Number of separable partitions of n in which the number of distinct (repeatable) parts <= 6.

Original entry on oeis.org

1, 1, 2, 3, 5, 6, 10, 14, 19, 26, 37, 49, 66, 87, 116, 152, 198, 254, 329, 422, 536, 678, 858, 1077, 1349, 1681, 2089, 2586, 3191, 3922, 4810, 5877, 7155, 8684, 10514, 12686, 15256, 18294, 21869, 26068, 30974, 36700, 43355, 51085, 59984, 70280, 82081, 95647
Offset: 1

Views

Author

Clark Kimberling, May 17 2019

Keywords

Comments

A partition is separable if there is an ordering of its parts in which no consecutive parts are identical. See A325534 for a guide to related sequences.

Crossrefs

Programs

  • Mathematica
    (separable=Table[Map[#[[1]]&,Select[Map[{#,Quotient[(1+Length[#]),Max[Map[Length,Split[#]]]]}&,IntegerPartitions[nn]],#[[2]]>1&]],{nn,35}]);
    Map[Length[Select[Map[{#,Length[Union[#]]}&,#],#[[2]]<=6&]]&,separable]
    (* Peter J. C. Moses, May 08 2019 *)
Showing 1-10 of 10 results.