A316313 -id:A316313 - cp's OEIS frontend

A316400 Number of strict integer partitions of n that are knapsack (every subset has a different sum) but not every subset has a different average.

0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 4, 1, 2, 4, 6, 4, 13, 6, 13, 17, 15, 12, 31, 26, 27, 23, 36, 41, 56, 39, 47, 74, 71, 55, 101, 94, 110, 97, 145, 148, 189, 142, 214, 232, 280, 206, 362, 332, 414, 347, 504, 469, 658, 492, 726, 697, 867, 687, 1100, 933

Offset: 1

Gus Wiseman, Jul 01 2018

nonn

			The a(21) = 13 partitions:
(8,7,6), (9,7,5), (10,7,4), (11,7,3), (12,7,2), (13,7,1),
(7,6,5,3), (8,6,4,3), (9,7,4,1), (10,6,3,2), (11,6,3,1), (12,4,3,2), (12,5,3,1).

Cf. A000009, A108917, A275972, A299702, A301899, A301900, A316271, A316313, A316314, A316399, A316401.

Table[Length[Select[IntegerPartitions[n],UnsameQ@@#&&UnsameQ@@Total/@Union[Subsets[#]]&&!UnsameQ@@Mean/@Union[Subsets[#]]&]],{n,20}]

A319327 Heinz numbers of integer partitions such that every distinct submultiset has a different LCM.

Original entry on oeis.org

1, 2, 3, 5, 7, 11, 13, 15, 17, 19, 23, 29, 31, 33, 35, 37, 41, 43, 47, 51, 53, 55, 59, 61, 67, 69, 71, 73, 77, 79, 83, 85, 89, 91, 93, 95, 97, 101, 103, 107, 109, 113, 119, 123, 127, 131, 137, 139, 141, 143, 145, 149, 151, 155, 157, 161, 163, 165, 167, 173

Offset: 1

Gus Wiseman, Sep 17 2018

nonn

Note that such a Heinz number is necessarily squarefree, as such a partition is necessarily strict.
The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).
First differs from A304713 (Heinz numbers of pairwise indivisible partitions) at A304713(642) = 2093, which is absent from this sequence because its prime indices are {4,6,9} and LCM(4,9) = LCM(4,6,9) = 36.

			The sequence of partitions whose Heinz numbers are in the sequence begins: (), (1), (2), (3), (4), (5), (6), (3,2), (7), (8), (9), (10), (11), (5,2), (4,3), (12), (13), (14), (15), (7,2).

Cf. A056239, A108917, A122768, A275972, A299702, A301899, A301900, A304713, A316313, A319315, A319319, A319320.

primeMS[n_]:=If[n===1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[100],UnsameQ@@LCM@@@Union[Subsets[primeMS[#]]]&]

A316364 Number of factorizations of n into factors > 1 such that every distinct submultiset of the factors has a different average.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 2, 2, 1, 3, 1, 3, 2, 2, 1, 4, 1, 2, 2, 3, 1, 5, 1, 3, 2, 2, 2, 5, 1, 2, 2, 5, 1, 5, 1, 3, 3, 2, 1, 6, 1, 3, 2, 3, 1, 5, 2, 5, 2, 2, 1, 8, 1, 2, 3, 4, 2, 5, 1, 3, 2, 5, 1, 9, 1, 2, 3, 3, 2, 5, 1, 6, 2, 2, 1, 9, 2, 2, 2, 5, 1, 9, 2, 3, 2, 2, 2, 10, 1, 3, 3, 5, 1, 5, 1, 5, 4

Offset: 1

Gus Wiseman, Jun 30 2018

nonn

Note that such a factorization is necessarily strict.

			The a(80) = 6 factorizations are (80), (10*8), (16*5), (20*4), (40*2), (10*4*2).

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A001055, A108917, A275972, A276024, A284640, A292886, A293627, A294150, A316313, A316314, A316365.

facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];
Table[Length[Select[facs[n],UnsameQ@@Mean/@Union[Subsets[#]]&]],{n,50}]

choosebybits(v,m) = { my(s=vector(hammingweight(m)),i=j=1); while(m>0,if(m%2,s[j] = v[i];j++); i++; m >>= 1); s; };
hasdupavgs(v) = { my(avgs=Map(), k); for(i=1,(2^(#v))-1,k = (vecsum(choosebybits(v,i))/hammingweight(i)); if(mapisdefined(avgs,k),return(i),mapput(avgs,k,i))); (0); };
A316364(n, m=n, facs=List([])) = if(1==n, (0==hasdupavgs(Vec(facs))), my(s=0, newfacs); fordiv(n, d, if((d>1)&&(d<=m), newfacs = List(facs); listput(newfacs,d); s += A316364(n/d, d, newfacs))); (s)); \\ Antti Karttunen, Sep 21 2018

More terms from Antti Karttunen, Sep 21 2018

A316365 Number of factorizations of n into factors > 1 such that every distinct subset of the factors has a different sum.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 4, 1, 2, 2, 4, 1, 4, 1, 4, 2, 2, 1, 7, 2, 2, 3, 4, 1, 4, 1, 6, 2, 2, 2, 9, 1, 2, 2, 7, 1, 5, 1, 4, 4, 2, 1, 9, 2, 4, 2, 4, 1, 6, 2, 7, 2, 2, 1, 10, 1, 2, 4, 9, 2, 5, 1, 4, 2, 4, 1, 14, 1, 2, 4, 4, 2, 5, 1, 11, 5, 2, 1, 9, 2, 2, 2, 7, 1, 10, 2, 4, 2, 2, 2, 15, 1, 4, 4, 9, 1, 5, 1, 7, 5

Offset: 1

Gus Wiseman, Jun 30 2018

nonn

Also the number of factorizations of n into factors > 1 which form a knapsack partition.

			The a(24) = 7 factorizations are (2*2*2*3), (2*2*6), (2*3*4), (2*12), (3*8), (4*6), (24).
The a(54) = 6 factorizations are (2*3*3*3), (2*3*9), (2*27), (3*18), (6*9), (54).

Antti Karttunen, Table of n, a(n) for n = 1..10080
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..100000

Cf. A001055, A108917, A275972, A292886, A293627, A294150, A299702, A316313, A316314, A316364.

facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];
Table[Length[Select[facs[n],UnsameQ@@Total/@Union[Subsets[#]]&]],{n,100}]

primeprodbybits(v,b) = { my(m=1,i=1); while(b>0,if(b%2, m *= prime(v[i])); i++; b >>= 1); (m); };
sumbybits(v,b) = { my(s=0,i=1); while(b>0,s += (b%2)*v[i]; i++; b >>= 1); (s); };
all_distinct_subsets_have_different_sums(v) = { my(m=Map(),s,pp); for(i=0,(2^#v)-1, pp = primeprodbybits(v,i); s = sumbybits(v,i); if(mapisdefined(m,s), if(mapget(m,s)!=pp, return(0)), mapput(m,s,pp))); (1); };
A316365(n, m=n, facs=List([])) = if(1==n, all_distinct_subsets_have_different_sums(Vec(facs)), my(s=0, newfacs); fordiv(n, d, if((d>1)&&(d<=m), newfacs = List(facs); listput(newfacs,d); s += A316365(n/d, d, newfacs))); (s)); \\ Antti Karttunen, Oct 08 2018

More terms from Antti Karttunen, Oct 08 2018

A316398 Number of distinct subset-averages of the integer partition with Heinz number n.

Original entry on oeis.org

1, 2, 2, 2, 2, 4, 2, 2, 2, 4, 2, 5, 2, 4, 4, 2, 2, 5, 2, 5, 4, 4, 2, 6, 2, 4, 2, 5, 2, 6, 2, 2, 4, 4, 4, 6, 2, 4, 4, 6, 2, 8, 2, 5, 5, 4, 2, 7, 2, 5, 4, 5, 2, 6, 4, 6, 4, 4, 2, 9, 2, 4, 5, 2, 4, 8, 2, 5, 4, 8, 2, 8, 2, 4, 5, 5, 4, 8, 2, 7, 2, 4, 2, 9, 4, 4, 4, 6, 2, 8, 4, 5, 4, 4, 4, 8, 2, 5, 5, 6, 2, 8, 2, 6, 6

Offset: 1

Gus Wiseman, Jul 01 2018

nonn

Although the average of an empty set is technically indeterminate, we consider it to be distinct from the other subset-averages.

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

			The a(60) = 9 distinct subset-averages of (3,2,1,1) are 0/0, 1, 4/3, 3/2, 5/3, 7/4, 2, 5/2, 3.

Cf. A032302, A056239, A108917, A275972, A276024, A296150, A299701, A301899, A301957, A316313.

One more than A316314.

primeMS[n_]:=If[n===1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Table[Length[Union[Mean/@Subsets[primeMS[n]]]],{n,100}]

A056239(n) = { my(f); if(1==n, 0, f=factor(n); sum(i=1, #f~, f[i,2] * primepi(f[i,1]))); }
A316398(n) = { my(m=Map(),s,k=0); fordiv(n,d,if((d>1)&&!mapisdefined(m,s = A056239(d)/bigomega(d)), mapput(m,s,s); k++)); (1+k); }; \\ Antti Karttunen, Sep 23 2018

a(n) = A316314(n) + 1.

More terms from Antti Karttunen, Sep 23 2018

A319335 Numerator of the average of the averages of all integer partitions of n.

Original entry on oeis.org

1, 3, 11, 31, 187, 131, 247, 1993, 4463, 3635, 395077, 24441, 81149, 10414421, 12868591, 10764151, 61170133, 419426561, 353495183, 3429826973, 29219934899, 5110021867, 142319532929, 606916707064, 87086496509, 4426308633083, 15954910019953, 38414031851849

Offset: 1

Gus Wiseman, Sep 17 2018

			The sequence of average averages begins: 1, 3/2, 11/6, 31/15, 187/84, 131/55, 247/100, 1993/770, 4463/1680, 3635/1323.

Andrew Howroyd, Table of n, a(n) for n = 1..500

Denominators are in A319336.

Cf. A056239, A067538, A237984, A296150, A316313, A316314, A316440.

Table[Numerator[Mean[Mean/@IntegerPartitions[n]]],{n,20}]

seq(n)={[numerator(poldegree(p)*subst(intformal(p/y)/p, y, 1)) | p <- Vec(-1+1/prod(k=1, n, 1 - x^k*y + O(x*x^n)))]} \\ Andrew Howroyd, Sep 19 2018

A319336 Denominator of the average of the averages of all integer partitions of n.

Original entry on oeis.org

1, 2, 6, 15, 84, 55, 100, 770, 1680, 1323, 141120, 8470, 27720, 3474900, 4228224, 3468465, 19459440, 131030900, 109156320, 1042578108, 8779605120, 1514663280, 41736380400, 175685635125, 24960905112, 1254125149200, 4476730258000, 10664476594200, 73326164511600

Offset: 1

Gus Wiseman, Sep 17 2018

			The sequence of average averages begins: 1, 3/2, 11/6, 31/15, 187/84, 131/55, 247/100, 1993/770, 4463/1680, 3635/1323.

Andrew Howroyd, Table of n, a(n) for n = 1..500

Numerators are in A319335.

Cf. A056239, A067538, A237984, A296150, A316313, A316314, A316440.

Table[Denominator[Mean[Mean/@IntegerPartitions[n]]],{n,20}]

seq(n)={[denominator(poldegree(p)*subst(intformal(p/y)/p, y, 1)) | p <- Vec(-1+1/prod(k=1, n, 1 - x^k*y + O(x*x^n)))]} \\ Andrew Howroyd, Sep 19 2018

A316361 FDH numbers of strict integer partitions such that not every distinct subset has a different average.

Original entry on oeis.org

24, 56, 60, 110, 120, 135, 140, 168, 210, 216, 224, 264, 270, 273, 280, 308, 312, 315, 330, 342, 360, 378, 384, 408, 420, 440, 456, 459, 480, 504, 520, 540, 546, 550, 552, 576, 585, 594, 600, 616, 630, 660, 672, 693, 696, 702, 728, 744, 756, 759, 760, 770, 780

Offset: 1

Gus Wiseman, Jun 30 2018

nonn

Let f(n) = A050376(n) be the n-th Fermi-Dirac prime. The FDH number of a strict integer partition (y_1,...,y_k) is f(y_1)*...*f(y_k).

			210 is the FDH number of (5,4,2,1), and the subsets {1,5}, and {2,4} have the same average, so 210 belongs to the data.

Cf. A050376, A064547, A108917, A213925, A275972, A299755, A299757, A301899, A301900, A316271, A316313, A316362.

nn=1000;
FDfactor[n_]:=If[n==1,{},Sort[Join@@Cases[FactorInteger[n],{p_,k_}:>Power[p,Cases[Position[IntegerDigits[k,2]//Reverse,1],{m_}->2^(m-1)]]]]];
FDprimeList=Array[FDfactor,nn,1,Union];FDrules=MapIndexed[(#1->#2[[1]])&,FDprimeList];
Select[Range[nn],!UnsameQ@@Mean/@Union[Subsets[FDfactor[#]/.FDrules]]&]

A316362 Heinz numbers of strict integer partitions such that not every distinct subset has a different average.

Original entry on oeis.org

30, 105, 110, 210, 238, 273, 330, 385, 390, 462, 506, 510, 546, 570, 627, 690, 714, 770, 806, 858, 870, 910, 930, 935, 966, 1001, 1110, 1131, 1155, 1190, 1230, 1254, 1290, 1326, 1330, 1365, 1394, 1410, 1430, 1482, 1495, 1518, 1590, 1729, 1770, 1785, 1786, 1794

Offset: 1

Gus Wiseman, Jun 30 2018

nonn

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

			462 is the Heinz number of (5,4,2,1), and the subsets {1,5}, and {2,4} have the same average, so 462 belongs to the sequence.

Cf. A032302, A056239, A108917, A122768, A275972, A276024, A296150, A299702, A301899, A316313, A316314, A316361.

primeMS[n_]:=If[n===1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
Select[Range[3000],SquareFreeQ[#]&&!UnsameQ@@Mean/@Union[Subsets[primeMS[#]]]&]

A316401 Number of strict integer partitions of n that are not knapsack (not every subset has a different sum) but every subset has a different average.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 0, 1, 0, 3, 1, 3, 2, 4, 2, 6, 6, 11, 9, 9, 10, 20, 16, 18, 17, 27, 24, 31, 29, 43, 31, 43, 40, 59, 52, 58, 61, 83, 68, 93, 80, 124, 99, 120, 109, 145, 151, 185, 160, 232, 163, 257, 229, 314, 280, 286, 310, 427, 385, 513, 333, 596

Offset: 1

Gus Wiseman, Jul 01 2018

nonn

			The a(22) = 11 partitions:
(11,6,5), (11,7,4), (11,8,3), (11,9,2), (11,10,1),
(11,5,4,2), (11,6,3,2), (11,8,2,1), (12,5,3,2), (12,5,4,1), (14,4,3,1).

Cf. A000009, A108917, A275972, A299702, A301899, A301900, A316271, A316313, A316314, A316399, A316400.

Table[Length[Select[IntegerPartitions[n],UnsameQ@@#&&!UnsameQ@@Total/@Union[Subsets[#]]&&UnsameQ@@Mean/@Union[Subsets[#]]&]],{n,20}]

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A316400 Number of strict integer partitions of n that are knapsack (every subset has a different sum) but not every subset has a different average.

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A319327 Heinz numbers of integer partitions such that every distinct submultiset has a different LCM.

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A316364 Number of factorizations of n into factors > 1 such that every distinct submultiset of the factors has a different average.

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A316365 Number of factorizations of n into factors > 1 such that every distinct subset of the factors has a different sum.

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A316398 Number of distinct subset-averages of the integer partition with Heinz number n.

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A319335 Numerator of the average of the averages of all integer partitions of n.

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A319336 Denominator of the average of the averages of all integer partitions of n.

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A316361 FDH numbers of strict integer partitions such that not every distinct subset has a different average.

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