A381870
Numbers whose prime indices have a unique multiset partition into sets with distinct sums.
Original entry on oeis.org
1, 2, 3, 5, 7, 11, 12, 13, 17, 18, 19, 20, 23, 28, 29, 31, 36, 37, 41, 43, 44, 45, 47, 50, 52, 53, 59, 61, 63, 67, 68, 71, 73, 75, 76, 79, 83, 89, 92, 97, 98, 99, 100, 101, 103, 107, 109, 113, 116, 117, 120, 124, 127, 131, 137, 139, 147, 148, 149, 151, 153
Offset: 1
For n = 600 the unique multiset partition is {{1},{1,3},{1,2,3}}. The unique factorization is 2*10*30.
Normal multiset partitions of this type are counted by
A381718, see
A279785.
For constant instead of strict blocks we have
A381991, ones in
A381635.
A003963 gives product of prime indices.
A122111 represents conjugation in terms of Heinz numbers.
A265947 counts refinement-ordered pairs of integer partitions.
A321469 counts factorizations with distinct sums of prime indices, ones
A166684.
-
hwt[n_]:=Total[Cases[FactorInteger[n],{p_,k_}:>PrimePi[p]*k]];
sfacs[n_]:=If[n<=1,{{}},Join@@Table[(Prepend[#,d]&)/@Select[sfacs[n/d],Min@@#>=d&],{d,Select[Rest[Divisors[n]],SquareFreeQ]}]];
Select[Range[100],Length[Select[sfacs[#],UnsameQ@@hwt/@#&]]==1&]
A381634
Number of multisets that can be obtained by taking the sum of each block of a set multipartition (multiset of sets) of the prime indices of n with distinct block-sums.
Original entry on oeis.org
1, 1, 1, 0, 1, 2, 1, 0, 0, 2, 1, 1, 1, 2, 2, 0, 1, 1, 1, 1, 2, 2, 1, 0, 0, 2, 0, 1, 1, 4, 1, 0, 2, 2, 2, 1, 1, 2, 2, 0, 1, 5, 1, 1, 1, 2, 1, 0, 0, 1, 2, 1, 1, 0, 2, 0, 2, 2, 1, 3, 1, 2, 1, 0, 2, 5, 1, 1, 2, 4, 1, 0, 1, 2, 1, 1, 2, 5, 1, 0, 0, 2, 1, 4, 2, 2, 2
Offset: 1
The prime indices of 120 are {1,1,2,3}, with 3 ways:
{{1},{1,2,3}}
{{1,2},{1,3}}
{{1},{2},{1,3}}
with block-sums: {1,6}, {3,4}, {1,2,4}, so a(120) = 3.
The prime indices of 210 are {1,2,3,4}, with 12 ways:
{{1,2,3,4}}
{{1},{2,3,4}}
{{2},{1,3,4}}
{{3},{1,2,4}}
{{4},{1,2,3}}
{{1,2},{3,4}}
{{1,3},{2,4}}
{{1},{2},{3,4}}
{{1},{3},{2,4}}
{{1},{4},{2,3}}
{{2},{3},{1,4}}
{{1},{2},{3},{4}}
with block-sums: {10}, {1,9}, {2,8}, {3,7}, {4,6}, {3,7}, {4,6}, {1,2,7}, {1,3,6}, {1,4,5}, {2,3,5}, {1,2,3,4}, of which 10 are distinct, so a(210) = 10.
A003963 gives product of prime indices.
A265947 counts refinement-ordered pairs of integer partitions.
Cf.
A000720,
A001222,
A002846,
A005117,
A116540,
A213242,
A213385,
A213427,
A299202,
A300385,
A317142,
A317143,
A318360.
-
hwt[n_]:=Total[Cases[FactorInteger[n],{p_,k_}:>PrimePi[p]*k]];
sfacs[n_]:=If[n<=1,{{}},Join@@Table[(Prepend[#,d]&)/@Select[sfacs[n/d],Min@@#>=d&],{d,Select[Rest[Divisors[n]],SquareFreeQ]}]];
Table[Length[Union[Sort[hwt/@#]&/@Select[sfacs[n],UnsameQ@@hwt/@#&]]],{n,100}]
A381715
Number of multisets that can be obtained by taking the sum of each block of a multiset partition of the prime indices of n into distinct constant blocks.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1
Offset: 1
The prime indices of 1728 are {1,1,1,1,1,1,2,2,2}, with multiset partitions into distinct constant blocks:
{{2,2,2},{1,1,1,1,1,1}}
{{1},{2,2,2},{1,1,1,1,1}}
{{2},{2,2},{1,1,1,1,1,1}}
{{1,1},{2,2,2},{1,1,1,1}}
{{1},{2},{2,2},{1,1,1,1,1}}
{{1},{1,1},{1,1,1},{2,2,2}}
{{2},{1,1},{2,2},{1,1,1,1}}
{{1},{2},{1,1},{2,2},{1,1,1}}
with sums:
{6,6}
{1,5,6}
{2,4,6}
{2,4,6}
{1,2,4,5}
{1,2,3,6}
{2,2,4,4}
{1,2,2,3,4}
of which 7 are distinct, so a(1728) = 7.
Positions of terms > 1 are
A046099.
For equal instead of distinct blocks we have
A362421.
For strict instead of constant blocks we have
A381441, before sums
A050326.
A003963 gives product of prime indices.
Cf.
A000720,
A001222,
A002846,
A005117,
A050342,
A213242,
A213385,
A293511,
A299202,
A300385,
A317142,
A381870.
-
prix[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
sps[{}]:={{}};sps[set:{i_,_}]:=Join@@Function[s,Prepend[#,s]&/@sps[Complement[set,s]]]/@Cases[Subsets[set],{i,_}];
mps[mset_]:=Union[Sort[Sort/@(#/.x_Integer:>mset[[x]])]&/@sps[Range[Length[mset]]]];
Table[Length[Union[Sort[Total/@#]&/@Select[mps[prix[n]],UnsameQ@@#&&And@@SameQ@@@#&]]],{n,100}]
A300486
Number of relatively prime or monic partitions of n.
Original entry on oeis.org
1, 2, 3, 4, 7, 8, 15, 18, 28, 35, 56, 64, 101, 120, 168, 210, 297, 348, 490, 583, 776, 946, 1255, 1482, 1952, 2335, 2981, 3581, 4565, 5387, 6842, 8119, 10086, 12013, 14863, 17527, 21637, 25525, 31083, 36695, 44583, 52256, 63261, 74171, 88932, 104303, 124754
Offset: 1
The a(6) = 8 relatively prime or monic partitions are (6), (51), (411), (321), (3111), (2211), (21111), (111111). Missing from this list are (42), (33), (222).
Cf.
A000837,
A001383,
A063834,
A093637,
A196545,
A281113,
A289501,
A300383,
A301462,
A301467,
A301480,
A302094,
A302698,
A302915,
A302916,
A302917.
-
Table[Length[Select[IntegerPartitions[n],Or[Length[#]===1,GCD@@#===1]&]],{n,20}]
-
a(n)={(n > 1) + sumdiv(n, d, moebius(d)*numbpart(n/d))} \\ Andrew Howroyd, Aug 29 2018
A301706
Number of rooted thrice-partitions of n.
Original entry on oeis.org
1, 1, 2, 4, 9, 19, 43, 91, 201, 422, 918, 1896, 4089, 8376, 17793, 36445, 76446, 155209, 324481, 655426, 1355220, 2741092, 5617505, 11291037, 23086423, 46227338, 93753196, 187754647, 378675055, 754695631, 1518414812, 3016719277, 6037006608, 11984729983
Offset: 1
The a(5) = 9 rooted thrice-partitions:
((2)), ((11)), ((1)()), (()()()),
((1))(), (()())(), (())(()),
(())()(),
()()()().
The a(6) = 19 rooted thrice-partitions:
((3)), ((21)), ((111)), ((2)()), ((11)()), ((1)(1)), ((1)()()), (()()()()),
((2))(), ((11))(), ((1)())(), (()()())(), ((1))(()), (()())(()),
((1))()(), (()())()(), (())(())(),
(())()()(),
()()()()().
Cf.
A000041,
A001383,
A002865,
A063834,
A093637,
A119442,
A196545,
A281113,
A289501,
A300383,
A301422,
A301462,
A301467,
A301480,
A301595,
A301598.
-
twire[n_]:=twire[n]=Sum[Times@@PartitionsP/@(ptn-1),{ptn,IntegerPartitions[n-1]}];
thrire[n_]:=Sum[Times@@twire/@ptn,{ptn,IntegerPartitions[n-1]}];
Array[thrire,30]
A381436
Irregular triangle read by rows where row k is the section-sum partition of the prime indices of n.
Original entry on oeis.org
1, 2, 1, 1, 3, 3, 4, 1, 1, 1, 2, 2, 4, 5, 3, 1, 6, 5, 5, 1, 1, 1, 1, 7, 3, 2, 8, 4, 1, 6, 6, 9, 3, 1, 1, 3, 3, 7, 2, 2, 2, 5, 1, 10, 6, 11, 1, 1, 1, 1, 1, 7, 8, 7, 3, 3, 12, 9, 8, 4, 1, 1, 13, 7, 14, 6, 1, 5, 2, 10, 15, 3, 1, 1, 1, 4, 4, 4, 3, 9, 7, 1, 16, 3, 2, 2
Offset: 1
The prime indices of 24 are (2,1,1,1), with sections ((2,1),(1),(1)), so row 24 is (3,1,1).
Triangle begins:
1: (empty)
2: 1
3: 2
4: 1 1
5: 3
6: 3
7: 4
8: 1 1 1
9: 2 2
10: 4
11: 5
12: 3 1
13: 6
14: 5
15: 5
16: 1 1 1 1
Rows appearing only once have Heinz numbers
A381434, more than once
A381435.
A003963 gives product of prime indices.
A122111 represents conjugation in terms of Heinz numbers.
-
prix[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
egs[y_]:=If[y=={},{},Table[Total[Select[Union[y],Count[y,#]>=i&]],{i,Max@@Length/@Split[y]}]];
Table[egs[prix[n]],{n,100}]
A382075
Numbers whose prime indices can be partitioned into a set of sets with distinct sums.
Original entry on oeis.org
1, 2, 3, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 26, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 50, 51, 52, 53, 55, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84
Offset: 1
The prime indices of 1080 are {1,1,1,2,2,2,3}, and {{1},{2},{1,2},{1,2,3}} is a partition into a set of sets with distinct sums, so 1080 is in the sequence.
Twice-partitions of this type are counted by
A279785, see also
A358914.
Normal multiset partitions into sets with distinct sums are counted by
A381718.
Partitions of this type are counted by
A381992.
For distinct blocks instead of block-sums we have
A382200, complement
A293243.
MM-numbers of multiset partitions into sets with distinct sums are
A382201.
Normal multisets of this type are counted by
A382216, see also
A382214.
A050320 counts multiset partitions of prime indices into sets.
A050326 counts multiset partitions of prime indices into distinct sets.
-
sps[{}]:={{}};sps[set:{i_,_}]:=Join@@Function[s,Prepend[#,s]& /@ sps[Complement[set,s]]]/@Cases[Subsets[set],{i,_}];
mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]& /@ sps[Range[Length[set]]]];
Select[Range[100],Length[Select[mps[prix[#]], And@@UnsameQ@@@#&&UnsameQ@@Total/@#&]]>0&]
A382200
Numbers that can be written as a product of distinct squarefree numbers.
Original entry on oeis.org
1, 2, 3, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 26, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 50, 51, 52, 53, 55, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84
Offset: 1
The prime indices of 1080 are {1,1,1,2,2,2,3}, and {{1},{2},{1,2},{1,2,3}} is a partition into a set of sets, so 1080 is in the sequence.
We have 18000 = 2*5*6*10*30, so 18000 is in the sequence.
Twice-partitions of this type are counted by
A279785, see also
A358914.
Normal multisets not of this type are counted by
A292432, strong
A292444.
The case of a unique choice is
A293511.
MM-numbers of multiset partitions into distinct sets are
A302494.
For distinct block-sums instead of blocks we have
A382075, counted by
A381992.
A050320 counts multiset partitions of prime indices into sets.
A050326 counts multiset partitions of prime indices into distinct sets.
-
N:= 1000: # to get all terms <= N
A:= Vector(N):
A[1]:= 1:
for n from 2 to N do
if numtheory:-issqrfree(n) then
S:= [$1..N/n]; T:= n*S; A[T]:= A[T]+A[S]
fi;
od:
remove(t -> A[t]=0, [$1..N]); # Robert Israel, Apr 21 2025
-
sqfacs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[sqfacs[n/d],Min@@#>d&]],{d,Select[Rest[Divisors[n]],SquareFreeQ]}]];
Select[Range[100],Length[sqfacs[#]]>0&]
A381440
Irregular triangle read by rows where row k is the Look-and-Say partition of the prime indices of n.
Original entry on oeis.org
1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 1
The prime indices of 24 are (2,1,1,1), with Look-and-Say partition (3,1,1), so row 24 is (3,1,1).
The prime indices of 36 are (2,2,1,1), with Look-and-Say partition (2,2,2), so row 36 is (2,2,2).
Triangle begins:
1: (empty)
2: 1
3: 1 1
4: 2
5: 1 1 1
6: 1 1 1
7: 1 1 1 1
8: 3
9: 2 2
10: 1 1 1 1
11: 1 1 1 1 1
12: 2 1 1
13: 1 1 1 1 1 1
14: 1 1 1 1 1
15: 1 1 1 1 1
16: 4
17: 1 1 1 1 1 1 1
18: 2 2 1
19: 1 1 1 1 1 1 1 1
Rows appearing only once have Heinz numbers
A381540, more than once
A381541.
A003963 gives product of prime indices.
A122111 represents conjugation in terms of Heinz numbers.
Cf.
A000720,
A003557,
A047966,
A071178,
A091602,
A116861,
A130091,
A181819,
A212166,
A238744,
A380955.
-
Table[Sort[Join@@Cases[FactorInteger[n],{p_,k_}:>ConstantArray[k,PrimePi[p]]]]//Reverse,{n,30}]
A382076
Number of integer partitions of n whose run-sums are not all equal.
Original entry on oeis.org
0, 0, 0, 1, 1, 5, 6, 13, 15, 27, 37, 54, 64, 99, 130, 172, 220, 295, 372, 488, 615, 788, 997, 1253, 1547, 1955, 2431, 3005, 3706, 4563, 5586, 6840, 8332, 10139, 12305, 14879, 17933, 21635, 26010, 31181, 37314, 44581, 53156, 63259, 75163, 89124, 105553, 124752, 147210
Offset: 0
The partition (3,2,1,1,1) has runs ((3),(2),(1,1,1)) with sums (3,2,3) so is counted under a(8).
The a(3) = 1 through a(8) = 15 partitions:
(21) (31) (32) (42) (43) (53)
(41) (51) (52) (62)
(221) (321) (61) (71)
(311) (411) (322) (332)
(2111) (2211) (331) (431)
(21111) (421) (521)
(511) (611)
(2221) (3221)
(3211) (3311)
(4111) (4211)
(22111) (5111)
(31111) (22211)
(211111) (32111)
(311111)
(2111111)
For distinct instead of equal block-sums we have
A381717.
A050361 counts factorizations into distinct prime powers, see
A381715.
A304405 counts partitions with weakly decreasing run-sums, ranks
A357875.
A304406 counts partitions with weakly increasing run-sums, ranks
A357861.
A304428 counts partitions with strictly decreasing run-sums, ranks
A357862.
A304430 counts partitions with strictly increasing run-sums, ranks
A357864.
A326534 ranks multiset partitions with a common sum.
A353837 counts partitions with distinct run-sums.
A354584 lists run-sums of weakly increasing prime indices.
A355743 ranks multiset partitions into constant blocks.
Cf.
A000688,
A005117,
A006171,
A047966,
A279784,
A381453,
A381455,
A381635,
A381636,
A381994,
A382204.
-
Table[Length[Select[IntegerPartitions[n],!SameQ@@Total/@Split[#]&]],{n,0,15}]
Comments