A049610 -id:A049610 - cp's OEIS frontend

A336103 Number of separable multisets of size n covering an initial interval of positive integers.

1, 1, 1, 3, 5, 13, 24, 56, 108, 236, 464, 976, 1936, 3984, 7936, 16128, 32192, 64960, 129792, 260864, 521472, 1045760, 2091008, 4188160, 8375296, 16763904, 33525760, 67080192, 134156288, 268374016, 536739840, 1073610752, 2147205120, 4294688768, 8589344768, 17179279360, 34358493184

Offset: 0

Gus Wiseman, Jul 09 2020

A multiset is separable if it has a permutation that is an anti-run, meaning there are no adjacent equal parts.
Alternatively, a multiset is separable if its greatest multiplicity is greater than the sum of its remaining multiplicities plus one. Hence a(n) is the number of compositions of n whose greatest part is at most one more than the sum of its other parts. For example, the a(1) = 1 through a(5) = 13 compositions are:
  (1)  (11)  (12)   (22)    (23)
             (21)   (112)   (32)
             (111)  (121)   (113)
                    (211)   (122)
                    (1111)  (131)
                            (212)
                            (221)
                            (311)
                            (1112)
                            (1121)
                            (1211)
                            (2111)
                            (11111)

			The a(1) = 1 through a(5) = 13 separable multisets:
  {1}  {1,2}  {1,1,2}  {1,1,2,2}  {1,1,1,2,2}
              {1,2,2}  {1,1,2,3}  {1,1,1,2,3}
              {1,2,3}  {1,2,2,3}  {1,1,2,2,2}
                       {1,2,3,3}  {1,1,2,2,3}
                       {1,2,3,4}  {1,1,2,3,3}
                                  {1,1,2,3,4}
                                  {1,2,2,2,3}
                                  {1,2,2,3,3}
                                  {1,2,2,3,4}
                                  {1,2,3,3,3}
                                  {1,2,3,3,4}
                                  {1,2,3,4,4}
                                  {1,2,3,4,5}

Michael De Vlieger, Table of n, a(n) for n = 0..3322
Index entries for linear recurrences with constant coefficients, signature (2,4,-8,-4,8).

The inseparable version is A336102.
The strong (weakly decreasing multiplicities) case is A336106.
Sequences covering an initial interval are A000670.
Anti-run compositions are A003242.
Anti-run patterns are A005649.
Separable partitions are A325534.
Inseparable partitions are A325535.
Inseparable factorizations are A333487.
Anti-run compositions are ranked by A333489.
Heinz numbers of inseparable partitions are A335448.
Cf. A001792, A019472, A025065, A049610, A052841, A106351, A269134, A292884, A335126, A335433, A335452.

allnorm[n_]:=If[n<=0,{{}},Function[s,Array[Count[s,y_/;y<=#]+1&,n]]/@Subsets[Range[n-1]+1]];
sepQ[m_]:=Select[Permutations[m],!MatchQ[#,{_,x_,x_,_}]&]!={};
Table[Length[Select[allnorm[n],sepQ]],{n,0,5}]
(* or *)
Table[Length[Join@@Permutations/@Select[IntegerPartitions[n],With[{mx=Max@@#},mx<=1+Total[DeleteCases[#,mx,{1},1]]]&]],{n,0,15}] (* or *)
CoefficientList[Series[(x - 1) (2 x^5 + 7 x^4 - 5 x^2 + 1)/((2 x - 1) (2 x^2 - 1)^2), {x, 0, 36}], x] (* Michael De Vlieger, Apr 07 2021 *)

a(n) = 2^(n-1) - (floor(n/2)+1) * 2^(floor(n/2)-2) for n >= 2. - David A. Corneth, Jul 09 2020
From Chai Wah Wu, Apr 07 2021: (Start)
a(n) = 2*a(n-1) + 4*a(n-2) - 8*a(n-3) - 4*a(n-4) + 8*a(n-5) for n > 6.
G.f.: (x - 1)*(2*x^5 + 7*x^4 - 5*x^2 + 1)/((2*x - 1)*(2*x^2 - 1)^2). (End)

a(26)-a(36) from David A. Corneth, Jul 09 2020

A336102 Number of inseparable multisets of size n covering an initial interval of positive integers.

Original entry on oeis.org

0, 0, 1, 1, 3, 3, 8, 8, 20, 20, 48, 48, 112, 112, 256, 256, 576, 576, 1280, 1280, 2816, 2816, 6144, 6144, 13312, 13312, 28672, 28672, 61440, 61440, 131072, 131072, 278528, 278528, 589824, 589824, 1245184, 1245184, 2621440, 2621440, 5505024, 5505024, 11534336

Offset: 0

Gus Wiseman, Jul 08 2020

nonn

A multiset is separable if it has a permutation that is an anti-run, meaning there are no adjacent equal parts.
Alternatively, a multiset is separable if its greatest multiplicity is greater than the sum of its remaining multiplicities plus one.
Also the number of compositions of n whose greatest part is greater than the sum of its remaining parts plus one. For example, the a(2) = 1 through a(7) = 8 compositions are:
  (2)  (3)  (4)    (5)    (6)      (7)
            (1,3)  (1,4)  (1,5)    (1,6)
            (3,1)  (4,1)  (2,4)    (2,5)
                          (4,2)    (5,2)
                          (5,1)    (6,1)
                          (1,1,4)  (1,1,5)
                          (1,4,1)  (1,5,1)
                          (4,1,1)  (5,1,1)

			The a(2) = 1 through a(7) = 8 multisets:
  {11}  {111}  {1111}  {11111}  {111111}  {1111111}
               {1112}  {11112}  {111112}  {1111112}
               {1222}  {12222}  {111122}  {1111122}
                                {111123}  {1111123}
                                {112222}  {1122222}
                                {122222}  {1222222}
                                {122223}  {1222223}
                                {123333}  {1233333}

Michael De Vlieger, Table of n, a(n) for n = 0..6625
Index entries for linear recurrences with constant coefficients, signature (0,4,0,-4).

The strong (weakly decreasing multiplicities) case is A025065.
The bisection is A049610.
The separable version is A336103.
Sequences covering an initial interval are A000670.
Anti-run compositions are A003242.
Anti-run patterns are A005649.
Separable partitions are A325534.
Inseparable partitions are A325535.
Inseparable factorizations are A333487.
Anti-run compositions are ranked by A333489.
Heinz numbers of inseparable partitions are A335448.
Cf. A001792, A019472, A052841, A106351, A124767, A269134, A292884, A335433, A335126, A335452, A335548.

Table[Length[Join@@Permutations/@Select[IntegerPartitions[n],With[{mx=Max@@#},mx>1+Total[DeleteCases[#,mx,{1},1]]]&]],{n,0,15}]
(* Second program: *)
CoefficientList[Series[x^2*(1 - x) (x + 1)^2/(2 x^2 - 1)^2, {x, 0, 43}], x] (* Michael De Vlieger, Apr 07 2021 *)

a(2*n) = a(2*n + 1) = A049610(n + 1).
a(n) = 2^(n-1) - A336103(n).
A001792 repeated for n > 1. David A. Corneth, Jul 09 2020
From Chai Wah Wu, Apr 07 2021: (Start)
a(n) = 4*a(n-2) - 4*a(n-4) for n > 5.
G.f.: x^2*(1 - x)*(x + 1)^2/(2*x^2 - 1)^2. (End)

A336106 Number of integer partitions of n whose greatest part is at most one more than the sum of the other parts.

Original entry on oeis.org

1, 1, 1, 2, 3, 5, 7, 11, 15, 23, 30, 44, 58, 82, 105, 146, 186, 252, 318, 423, 530, 695, 863, 1116, 1380, 1763, 2164, 2738, 3345, 4192, 5096, 6334, 7665, 9459, 11395, 13968, 16765, 20425, 24418, 29588, 35251, 42496, 50460, 60547, 71669, 85628

Offset: 0

Gus Wiseman, Jul 09 2020

nonn

Also the number of separable strong multisets of length n covering an initial interval of positive integers. A multiset is separable if it has a permutation that is an anti-run, meaning there are no adjacent equal parts.

			The a(1) = 1 through a(8) = 15 partitions:
  (1)  (11)  (21)   (22)    (32)     (33)      (43)       (44)
             (111)  (211)   (221)    (222)     (322)      (332)
                    (1111)  (311)    (321)     (331)      (422)
                            (2111)   (2211)    (421)      (431)
                            (11111)  (3111)    (2221)     (2222)
                                     (21111)   (3211)     (3221)
                                     (111111)  (4111)     (3311)
                                               (22111)    (4211)
                                               (31111)    (22211)
                                               (211111)   (32111)
                                               (1111111)  (41111)
                                                          (221111)
                                                          (311111)
                                                          (2111111)
                                                          (11111111)

The inseparable version is A025065.
The Heinz numbers of these partitions are A335127.
The non-strong version is A336103.
Sequences covering an initial interval are A000670.
Anti-run compositions are A003242.
Anti-run patterns are A005649.
Separable partitions are A325534.
Inseparable partitions are A325535.
Separable factorizations are A335434.
Heinz numbers of separable partitions are A335433.
Cf. A049610, A106351, A292884, A335126, A335433, A335452, A335548, A336102.

Table[Length[Select[IntegerPartitions[n],2*Max@@#<=1+n&]],{n,0,15}]

A287879 Irregular triangle read by rows: normalized dimensions of certain generalized quadratic residue codes of length n.

Original entry on oeis.org

2, 4, 2, 8, 6, 16, 16, 18, 32, 40, 50, 64, 96, 132, 146, 128, 224, 336, 406, 256, 512, 832, 1088, 1186, 512, 1152, 2016, 2832, 3330, 1024, 2560, 4800, 7200, 9060, 9762, 2048, 5632, 11264, 17952, 24024, 27654, 4096, 12288, 26112, 44032, 62352, 76176, 81330, 8192, 26624, 59904, 106496, 158912, 204984, 232050, 16384, 57344, 136192, 254464, 398720, 540736, 645540, 684210

Offset: 1

N. J. A. Sloane, Jun 18 2017

			Triangle begins:
[2],
[4, 2],
[8, 6],
[16, 16, 18],
[32, 40, 50],
[64, 96, 132, 146],
[128, 224, 336, 406],
[256, 512, 832, 1088, 1186],
[512, 1152, 2016, 2832, 3330],
[1024, 2560, 4800, 7200, 9060, 9762],
[2048, 5632, 11264, 17952, 24024, 27654],
[4096, 12288, 26112, 44032, 62352, 76176, 81330],
[8192, 26624, 59904, 106496, 158912, 204984, 232050],
[16384, 57344, 136192, 254464, 398720, 540736, 645540, 684210],
...

Harold N. Ward, Quadratic residue codes in their prime, Journal of Algebra, 150.1 (1992): 87-100. See Table I.

The 0th column is A000079; column 1 is essentially the same as A057711 or A129952, and is also essentially twice A001792 or A049610.

Row sums are twice A287880.

g:=proc(m,w) local k;
if w=0 then 2^m else
2^m*add( (m/(m-w))*binomial(w-1,w-k)*binomial(m-w,k)/4^k, k=1..w);
fi;
end;
for n from 1 to 14 do
lprint( [seq(g(n,w),w=0..floor(n/2))]);
od;

See Ward, pp. 99-100, or the Maple code below.

cp's OEIS Frontend

A336103 Number of separable multisets of size n covering an initial interval of positive integers.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Programs

Mathematica

Formula

Extensions

A336102 Number of inseparable multisets of size n covering an initial interval of positive integers.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Programs

Mathematica

Formula

A336106 Number of integer partitions of n whose greatest part is at most one more than the sum of the other parts.

Views

Author

Keywords

Comments

Examples

Crossrefs

Programs

Mathematica

A287879 Irregular triangle read by rows: normalized dimensions of certain generalized quadratic residue codes of length n.

Views

Author

Keywords

Examples

Links

Crossrefs

Programs

Maple

Formula